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Tal A, Bischoff T, Pasquarello A. Absolute energy levels of liquid water from many-body perturbation theory with effective vertex corrections. Proc Natl Acad Sci U S A 2024; 121:e2311472121. [PMID: 38427604 DOI: 10.1073/pnas.2311472121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 01/31/2024] [Indexed: 03/03/2024] Open
Abstract
We demonstrate the importance of addressing the Γ vertex and thus going beyond the GW approximation for achieving the energy levels of liquid water in many-body perturbation theory. In particular, we consider an effective vertex function in both the polarizability and the self-energy, which does not produce any computational overhead compared with the GW approximation. We yield the band gap, the ionization potential, and the electron affinity in good agreement with experiment and with a hybrid functional description. The achieved electronic structure and dielectric screening further lead to a good description of the optical absorption spectrum, as obtained through the solution of the Bethe-Salpeter equation. In particular, the experimental peak position of the exciton is accurately reproduced.
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Affiliation(s)
- Alexey Tal
- Chaire de Simulation à l'Echelle Atomique, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Thomas Bischoff
- Chaire de Simulation à l'Echelle Atomique, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Alfredo Pasquarello
- Chaire de Simulation à l'Echelle Atomique, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
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2
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Chuang TH, Hsu CC, Chiu WS, Jhuang JS, Yeh IC, Chen RS, Gwo S, Wei DH. Performance of a photoelectron momentum microscope in direct- and momentum-space imaging with ultraviolet photon sources. J Synchrotron Radiat 2024; 31:195-201. [PMID: 38038695 PMCID: PMC10833436 DOI: 10.1107/s1600577523009761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023]
Abstract
The Photoelectron-Related Image and Nano-Spectroscopy (PRINS) endstation located at the Taiwan Photon Source beamline 27A2 houses a photoelectron momentum microscope capable of performing direct-space imaging, momentum-space imaging and photoemission spectroscopy with position sensitivity. Here, the performance of this microscope is demonstrated using two in-house photon sources - an Hg lamp and He(I) radiation - on a standard checkerboard-patterned specimen and an Au(111) single crystal, respectively. By analyzing the intensity profile of the edge of the Au patterns, the Rashba-splitting of the Au(111) Shockley surface state at 300 K, and the photoelectron intensity across the Fermi edge at 80 K, the spatial, momentum and energy resolution were estimated to be 50 nm, 0.0172 Å-1 and 26 meV, respectively. Additionally, it is shown that the band structures acquired in either constant energy contour mode or momentum-resolved photoemission spectroscopy mode were in close agreement.
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Affiliation(s)
- Tzu-Hung Chuang
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Chuan-Che Hsu
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Wei-Sheng Chiu
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan
| | | | - I-Chun Yeh
- Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan
| | - Ruei-San Chen
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan
| | - Shanjr Gwo
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan
| | - Der-Hsin Wei
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
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3
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Ahmad M, Cruguel H, Ahmadpour M, Vannucchi N, Samie NM, Leuillet C, Generalov A, Li Z, Madsen M, Witkowski N. Uncovering the Electronic State Interplay at Metal Oxide Electron Transport Layer/Nonfullerene Acceptor Interfaces in Stable Organic Photovoltaic Devices. ACS Appl Mater Interfaces 2023; 15:55065-55072. [PMID: 37972316 DOI: 10.1021/acsami.3c11103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The implementation of sputter-deposited TiOx as an electron transport layer in nonfullerene acceptor-based organic photovoltaics has been shown to significantly increase the long-term stability of devices compared to conventional solution-processed ZnO due to a decreased photocatalytic activity of the sputtered TiOx. In this work, we utilize synchrotron-based photoemission and absorption spectroscopies to investigate the interface between the electron transport layer, TiOx prepared by magnetron sputtering, and the nonfullerene acceptor, ITIC, prepared in situ by spray deposition to study the electronic state interplay and defect states at this interface. This is used to unveil the mechanisms behind the decreased photocatalytic activity of the sputter-deposited TiOx and thus also the increased stability of the organic solar cell devices. The results have been compared to similar measurements on anatase TiOx since anatase TiOx is known to have a strong photocatalytic activity. We show that the deposition of ITIC on top of the sputter-deposited TiOx results in an oxidation of Ti3+ species in the TiOx and leads to the emergence of a new O 1s peak that can be attributed to the oxygen in ITIC. In addition, increasing the thickness of ITIC on TiOx leads to a shift in the O 1s and C 1s core levels toward higher binding energies, which is consistent with electron transfer at the interface. Resonant photoemission at the Ti L-edge shows that oxygen vacancies in sputtered TiOx lie mostly in the surface region, which contrasts the anatase TiOx where an equal distribution between surface and subsurface oxygen vacancies is observed. Furthermore, it is shown that the subsurface oxygen vacancies in sputtered TiOx are strongly reduced after ITIC deposition, which can reduce the photocatalytic activity of the oxide, while the oxygen vacancies in model anatase TiOx are not affected upon ITIC deposition. This difference can explain the inferior photocatalytic activity of the sputter-deposited TiOx and thus also the increased stability of devices with sputter-deposited TiOx used as an electron transport layer.
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Affiliation(s)
- Mariam Ahmad
- SDU Centre for Advanced Photovoltaics and Thin-Film Energy Devices (SDU CAPE), Mads Clausen Institute, University of Southern Denmark, Alsion 2, So̷nderborg DK-6400, Denmark
- SDU Climate Cluster, University of Southern Denmark, Odense 5230, Denmark
| | - Hervé Cruguel
- UMR CNRS 7588, Institut des Nanosciences de Paris, Sorbonne Université, Paris F-75005, France
| | - Mehrad Ahmadpour
- SDU Centre for Advanced Photovoltaics and Thin-Film Energy Devices (SDU CAPE), Mads Clausen Institute, University of Southern Denmark, Alsion 2, So̷nderborg DK-6400, Denmark
| | - Noemi Vannucchi
- UMR CNRS 7588, Institut des Nanosciences de Paris, Sorbonne Université, Paris F-75005, France
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 752 36,Sweden
| | - Nahed Mohammad Samie
- UMR CNRS 7588, Institut des Nanosciences de Paris, Sorbonne Université, Paris F-75005, France
| | - Céline Leuillet
- UMR CNRS 7588, Institut des Nanosciences de Paris, Sorbonne Université, Paris F-75005, France
| | | | - Zheshen Li
- ISA, Centre for Storage Ring Facilities, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Bldg. 1520, Aarhus C DK-8000, Denmark
| | - Morten Madsen
- SDU Centre for Advanced Photovoltaics and Thin-Film Energy Devices (SDU CAPE), Mads Clausen Institute, University of Southern Denmark, Alsion 2, So̷nderborg DK-6400, Denmark
- SDU Climate Cluster, University of Southern Denmark, Odense 5230, Denmark
| | - Nadine Witkowski
- UMR CNRS 7588, Institut des Nanosciences de Paris, Sorbonne Université, Paris F-75005, France
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Jiang P, Zheng W, Li X, Zhang L, Liu Y, Wang Y, Li Y, Gao Y, Yang H, Liu Y, Gong Q, Wu C. Imaging and Controlling Ultrafast Electron Pulses Emitted from Plasmonic Nanostructures. Nano Lett 2023; 23:7327-7333. [PMID: 37535438 DOI: 10.1021/acs.nanolett.3c01644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
We experimentally study photoemission from gold nanodisk arrays using space-, time-, and energy-resolved photoemission electron microscopy. When excited by a plasmonic resonant infrared (IR) laser pulse, plasmonic hotspots are generated owing to local surface plasmon resonance. Photoelectrons emitted from each plasmonic hotspot form a nanoscale and ultrashort electron pulse. When the system is excited by an extreme ultraviolet (EUV) laser pulse, a uniformly distributed photoelectron cloud is formed across the sample surface. When excited by the IR and EUV laser pulses together, both the photoemission image and kinetic energy vary significantly for the IR laser-generated electrons depending on the time delay between the two laser pulses. These observations are well explained by the Coulomb interaction with the EUV laser-generated electron cloud. Our study offers a feasible approach to manipulate the energy of electron pulse emitted from a plasmonic nanostructure on an ultrafast time scale.
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Affiliation(s)
- Pengzuo Jiang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Wei Zheng
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Xiaofang Li
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Linfeng Zhang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Yu Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Yang Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Yaolong Li
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Yunan Gao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Hong Yang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Yunquan Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Chengyin Wu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
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Zapata R, Balestrieri M, Gozhyk I, Montigaud H, Lazzari R. On the O 2 "Surfactant" Effect during Ag/SiO 2 Magnetron Sputtering Deposition: The Point of View of In Situ and Real-Time Measurements. ACS Appl Mater Interfaces 2023. [PMID: 37480335 DOI: 10.1021/acsami.3c05689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
The use of gaseous species has been proposed in the literature to counteract the three-dimensional growth tendency of noble metals on dielectric substrates and favor an earlier percolation without compromising electrical properties. This "surfactant" effect is rationalized herein in the case of O2 presence during magnetron sputtering deposition of Ag films on SiO2. In situ and real-time techniques (X-ray photoemission, film resistivity, UV-visible optical spectroscopy) and ex situ characterizations (X-ray diffraction and transmission electron microscopy) were combined to scrutinize the impact of O2 addition in the gas flow (%O2), revealing three regimes of evolution of film resistivity, morphology, structure, and chemical composition. At low oxygen flow conditions (%O2 < 4), the observed drastic decrease of the percolation threshold is assigned to a combination of (i) a change in nanoparticle density, wetting, and crystallographic texture and (ii) a delayed coalescence effect. The driving force is ascribed to the presence of specific adsorbed oxygen moieties, the nature of which starts evolving at intermediate oxygen flow conditions (10 ≤ %O2 < 20). At high oxygen flow (20 ≤ %O2 < 40), the found detrimental impact on film resistivity is assigned to an actual oxidation in the form of a Ag2O-like poorly crystallized compound. For all %O2, a composition gradient is observed across the film thickness, with a more metallic Ag at the substrate interface. A correlation between percolation and the nature of the detected O moieties is observed. In parallel to an oxygen spillover mechanism, this gradient can be explained by the competition between different surface processes occurring before percolation, namely, aggregation, metal oxidation, and substrate reactivity. Such findings pave the way to a rational use of O2 as a modifier for Ag growth.
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Affiliation(s)
- Ramiro Zapata
- Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain Recherche, 39 Quai Lucien Lefranc BP 135, F-93303 Aubervilliers, France
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France
| | - Matteo Balestrieri
- Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain Recherche, 39 Quai Lucien Lefranc BP 135, F-93303 Aubervilliers, France
| | - Iryna Gozhyk
- Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain Recherche, 39 Quai Lucien Lefranc BP 135, F-93303 Aubervilliers, France
| | - Hervé Montigaud
- Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain Recherche, 39 Quai Lucien Lefranc BP 135, F-93303 Aubervilliers, France
| | - Rémi Lazzari
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France
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Wang H, Linghu J, Zou P, Wang X, Shen H, Hai B. Theoretical Study on the Photoemission Performance of a Transmission Mode In 0.15Ga 0.85As Photocathode in the Near-Infrared Region. Molecules 2023; 28:5262. [PMID: 37446922 DOI: 10.3390/molecules28135262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/06/2023] [Accepted: 07/06/2023] [Indexed: 07/15/2023] Open
Abstract
Benefiting from a high quantum efficiency, low thermal emittance, and large absorption coefficient, InxGa1-xAs is an excellent group III-V compound for negative electron affinity (NEA) photocathodes. As the emission layer, InxGa1-xAs, where x = 0.15, has the optimal performance for detection in the near-infrared (NIR) region. Herein, an NEA In0.15Ga0.85As photocathode with Al0.63Ga0.37As as the buffer layer is designed in the form of a transmission mode module. The electronic band structures and optical properties of In0.15Ga0.85As and Al0.63Ga0.37As are calculated based on density functional theory. The time response characteristics of the In0.15Ga0.85As photocathode have been fully investigated by changing the photoelectron diffusion coefficient, the interface recombination velocity, and the thickness of the emission layer. Our results demonstrate that the response time of the In0.15Ga0.85As photocathode can be reduced to 6.1 ps with an incident wavelength of 1064 nm. The quantum efficiency of the In0.15Ga0.85As photocathode is simulated by taking into account multilayer optical thin film theory. The results indicate that a high quantum efficiency can be obtained by parameter optimization of the emission layer. This paper provides significant theoretical support for the applications of semiconductor photocathodes in the near-infrared region, especially for the study of ultrafast responses in the photoemission process.
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Affiliation(s)
- Huan Wang
- School of Science, Chang'an University, Xi'an 710061, China
| | - Jiajun Linghu
- School of Science, Chang'an University, Xi'an 710061, China
| | - Pengfei Zou
- School of Science, Chang'an University, Xi'an 710061, China
| | - Xuezhi Wang
- School of Science, Chang'an University, Xi'an 710061, China
| | - Hao Shen
- School of Science, Chang'an University, Xi'an 710061, China
| | - Bingru Hai
- School of Physics, Northwest University, Xi'an 710069, China
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Nowik-Boltyk EM, Junghoefer T, Glaser M, Giangrisostomi E, Ovsyannikov R, Zhang S, Shu C, Rajca A, Calzolari A, Casu MB. Long-Term Degradation Mechanisms in Application-Implemented Radical Thin Films. ACS Appl Mater Interfaces 2023. [PMID: 37319383 DOI: 10.1021/acsami.3c02057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Blatter radical derivatives are very attractive due to their potential applications, ranging from batteries to quantum technologies. In this work, we focus on the latest insights regarding the fundamental mechanisms of radical thin film (long-term) degradation, by comparing two Blatter radical derivatives. We find that the interaction with different contaminants (such as atomic H, Ar, N, and O and molecular H2, N2, O2, H2O, and NH2) affects the chemical and magnetic properties of the thin films upon air exposure. Also, the radical-specific site, where the contaminant interaction takes place, plays a role. Atomic H and NH2 are detrimental to the magnetic properties of Blatter radicals, while the presence of molecular water influences more specifically the magnetic properties of the diradical thin films, and it is believed to be the major cause of the shorter diradical thin film lifetime in air.
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Affiliation(s)
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Mathias Glaser
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Erika Giangrisostomi
- Institute Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin, 12489 Berlin, Germany
| | - Ruslan Ovsyannikov
- Institute Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin, 12489 Berlin, Germany
| | - Shuyang Zhang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588, United States
| | | | - M Benedetta Casu
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
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8
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Røst HI, Tosi E, Strand FS, Åsland AC, Lacovig P, Lizzit S, Wells JW. Probing the Atomic Arrangement of Subsurface Dopants in a Silicon Quantum Device Platform. ACS Appl Mater Interfaces 2023; 15:22637-22643. [PMID: 37114767 PMCID: PMC10176322 DOI: 10.1021/acsami.2c23011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
High-density structures of subsurface phosphorus dopants in silicon continue to garner interest as a silicon-based quantum computer platform; however, a much-needed confirmation of their dopant arrangement has been lacking. In this work, we take advantage of the chemical specificity of X-ray photoelectron diffraction to obtain the precise structural configuration of P dopants in subsurface Si:P δ-layers. The growth of δ-layer systems with different levels of doping is carefully studied and verified using X-ray photoelectron spectroscopy and low-energy electron diffraction. Subsequent diffraction measurements reveal that in all cases, the subsurface dopants primarily substitute with Si atoms from the host material. Furthermore, no signs of carrier-inhibiting P-P dimerization can be observed. Our observations not only settle a nearly decade-long debate about the dopant arrangement but also demonstrate how X-ray photoelectron diffraction is surprisingly well suited for studying subsurface dopant structure. This work thus provides valuable input for an updated understanding of the behavior of Si:P δ-layers and the modeling of their derived quantum devices.
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Affiliation(s)
- Håkon I Røst
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
- Department of Physics and Technology, University of Bergen (UiB), Allégaten 55, 5007 Bergen, Norway
| | - Ezequiel Tosi
- Elettra-Sincrotrone Trieste, s.s. 14-km.163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC) C/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Frode S Strand
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
| | - Anna Cecilie Åsland
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
| | - Paolo Lacovig
- Elettra-Sincrotrone Trieste, s.s. 14-km.163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
| | - Silvano Lizzit
- Elettra-Sincrotrone Trieste, s.s. 14-km.163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
| | - Justin W Wells
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
- Department of Physics and Centre for Materials Science and Nanotechnology, University of Oslo (UiO), Oslo 0318, Norway
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9
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Al-Zubeidi A, Ostovar B, Carlin CC, Li BC, Lee SA, Chiang WY, Gross N, Dutta S, Misiura A, Searles EK, Chakraborty A, Roberts ST, Dionne JA, Rossky PJ, Landes CF, Link S. Mechanism for plasmon-generated solvated electrons. Proc Natl Acad Sci U S A 2023; 120:e2217035120. [PMID: 36626548 DOI: 10.1073/pnas.2217035120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Solvated electrons are powerful reducing agents capable of driving some of the most energetically expensive reduction reactions. Their generation under mild and sustainable conditions remains challenging though. Using near-ultraviolet irradiation under low-intensity one-photon conditions coupled with electrochemical and optical detection, we show that the yield of solvated electrons in water is increased more than 10 times for nanoparticle-decorated electrodes compared to smooth silver electrodes. Based on the simulations of electric fields and hot carrier distributions, we determine that hot electrons generated by plasmons are injected into water to form solvated electrons. Both yield enhancement and hot carrier production spectrally follow the plasmonic near-field. The ability to enhance solvated electron yields in a controlled manner by tailoring nanoparticle plasmons opens up a promising strategy for exploiting solvated electrons in chemical reactions.
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10
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Liu RY, Huang A, Sankar R, Hlevyack JA, Su CC, Weng SC, Lin MK, Chen P, Cheng CM, Denlinger JD, Mo SK, Fedorov AV, Chang CS, Jeng HT, Chuang TM, Chiang TC. Dirac Nodal Line in Hourglass Semimetal Nb 3SiTe 6. Nano Lett 2023; 23:380-388. [PMID: 36382909 DOI: 10.1021/acs.nanolett.2c03293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Glide-mirror symmetry in nonsymmorphic crystals can foster the emergence of novel hourglass nodal loop states. Here, we present spectroscopic signatures from angle-resolved photoemission of a predicted topological hourglass semimetal phase in Nb3SiTe6. Linear band crossings are observed at the zone boundary of Nb3SiTe6, which could be the origin of the nontrivial Berry phase and are consistent with a predicted glide quantum spin Hall effect; such linear band crossings connect to form a nodal loop. Furthermore, the saddle-like Fermi surface of Nb3SiTe6 observed in our results helps unveil linear band crossings that could be missed. In situ alkali-metal doping of Nb3SiTe6 also facilitated the observation of other band crossings and parabolic bands at the zone center correlated with accidental nodal loop states. Overall, our results complete the system's band structure, help explain prior Hall measurements, and suggest the existence of a nodal loop at the zone center of Nb3SiTe6.
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Affiliation(s)
- Ro-Ya Liu
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
- Institute of Physics, Academia Sinica, Taipei11529, Taiwan
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
- National Synchrotron Radiation Research Center, Hsinchu30076, Taiwan
| | - Angus Huang
- Department of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
| | - Raman Sankar
- Institute of Physics, Academia Sinica, Taipei11529, Taiwan
| | - Joseph Andrew Hlevyack
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
| | - Chih-Chuan Su
- Institute of Physics, Academia Sinica, Taipei11529, Taiwan
| | - Shih-Chang Weng
- National Synchrotron Radiation Research Center, Hsinchu30076, Taiwan
| | - Meng-Kai Lin
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
| | - Peng Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science and Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
| | - Cheng-Maw Cheng
- National Synchrotron Radiation Research Center, Hsinchu30076, Taiwan
| | - Jonathan D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Alexei V Fedorov
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | | | - Horng-Tay Jeng
- Institute of Physics, Academia Sinica, Taipei11529, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu30013, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei10617, Taiwan
| | | | - Tai-Chang Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois61801, United States
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11
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Peverini F, Bizzarri M, Boscardin M, Calcagnile L, Caprai M, Caricato AP, Cirrone GAP, Crivellari M, Cuttone G, Dunand S, Fanò L, Gianfelici B, Hammad O, Ionica M, Kanxheri K, Large M, Maruccio G, Menichelli M, Monteduro AG, Moscatelli F, Morozzi A, Pallotta S, Papi A, Passeri D, Petasecca M, Petringa G, Pis I, Quarta G, Rizzato S, Rossi A, Rossi G, Scorzoni A, Soncini C, Servoli L, Tacchi S, Talamonti C, Verzellesi G, Wyrsch N, Zema N, Pedio M. High-Resolution Photoemission Study of Neutron-Induced Defects in Amorphous Hydrogenated Silicon Devices. Nanomaterials (Basel) 2022; 12:3466. [PMID: 36234601 PMCID: PMC9565300 DOI: 10.3390/nano12193466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/20/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
In this paper, by means of high-resolution photoemission, soft X-ray absorption and atomic force microscopy, we investigate, for the first time, the mechanisms of damaging, induced by neutron source, and recovering (after annealing) of p-i-n detector devices based on hydrogenated amorphous silicon (a-Si:H). This investigation will be performed by mean of high-resolution photoemission, soft X-Ray absorption and atomic force microscopy. Due to dangling bonds, the amorphous silicon is a highly defective material. However, by hydrogenation it is possible to reduce the density of the defect by several orders of magnitude, using hydrogenation and this will allow its usage in radiation detector devices. The investigation of the damage induced by exposure to high energy irradiation and its microscopic origin is fundamental since the amount of defects determine the electronic properties of the a-Si:H. The comparison of the spectroscopic results on bare and irradiated samples shows an increased degree of disorder and a strong reduction of the Si-H bonds after irradiation. After annealing we observe a partial recovering of the Si-H bonds, reducing the disorder in the Si (possibly due to the lowering of the radiation-induced dangling bonds). Moreover, effects in the uppermost coating are also observed by spectroscopies.
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Affiliation(s)
- Francesca Peverini
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Marco Bizzarri
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Maurizio Boscardin
- INFN (Istituto Nazionale di Fisica Nucleare), TIPFA (Trento Institute for Fundamental Physics and Applications), Via Sommarive 14, 38123 Trento, Italy
- Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento, Italy
| | - Lucio Calcagnile
- CEDAD-Centro di Fisica Applicata, Datazione e Diagnostica, Dipartimento di Matematica e Fisica “Ennio de Giorgi”, Università del Salento e INFN-Sezione di Lecce, 73100 Lecce, Italy
| | - Mirco Caprai
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Anna Paola Caricato
- INFN (Istituto Nazionale di Fisica Nucleare) and Dipartimento di Fisica e Matematica dell’Università del Salento, Via per Arnesano, 73100 Lecce, Italy
| | | | | | - Giacomo Cuttone
- INFN (Istituto Nazionale di Fisica Nucleare) Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania, Italy
| | - Sylvain Dunand
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Electrical and Microengineering (IME), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
| | - Livio Fanò
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Benedetta Gianfelici
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Omar Hammad
- Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento, Italy
| | - Maria Ionica
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Keida Kanxheri
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Matthew Large
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, Wollongong, NSW 2522, Australia
| | - Giuseppe Maruccio
- INFN (Istituto Nazionale di Fisica Nucleare) and Dipartimento di Fisica e Matematica dell’Università del Salento, Via per Arnesano, 73100 Lecce, Italy
| | - Mauro Menichelli
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Anna Grazia Monteduro
- INFN (Istituto Nazionale di Fisica Nucleare) and Dipartimento di Fisica e Matematica dell’Università del Salento, Via per Arnesano, 73100 Lecce, Italy
| | - Francesco Moscatelli
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Istituto Officina dei Materiali-CNR, Basovizza SS-14, km 163.5, 34012 Trieste, Italy
| | - Arianna Morozzi
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Stefania Pallotta
- INFN (Istituto Nazionale di Fisica Nucleare) and Dipartimento di Fisica Scienze Biomediche Sperimentali e Cliniche “Mario Serio”, Viale Morgagni 50, 50135 Firenze, Italy
| | - Andrea Papi
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Daniele Passeri
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Ingegneria, Università Degli Studi di Perugia, via G.Duranti, 06125 Perugia, Italy
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, Wollongong, NSW 2522, Australia
| | - Giada Petringa
- INFN (Istituto Nazionale di Fisica Nucleare) Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania, Italy
| | - Igor Pis
- IOM-CNR, Istituto Officina dei Materiali, AREA Science Park Basovizza, 34149 Trieste, Italy
| | - Gianluca Quarta
- CEDAD-Centro di Fisica Applicata, Datazione e Diagnostica, Dipartimento di Matematica e Fisica “Ennio de Giorgi”, Università del Salento e INFN-Sezione di Lecce, 73100 Lecce, Italy
| | - Silvia Rizzato
- INFN (Istituto Nazionale di Fisica Nucleare) and Dipartimento di Fisica e Matematica dell’Università del Salento, Via per Arnesano, 73100 Lecce, Italy
| | - Alessandro Rossi
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Giulia Rossi
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Andrea Scorzoni
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Dipartimento di Ingegneria, Università Degli Studi di Perugia, via G.Duranti, 06125 Perugia, Italy
| | - Cristian Soncini
- Istituto Officina dei Materiali-CNR, Basovizza SS-14, km 163.5, 34012 Trieste, Italy
| | - Leonello Servoli
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
| | - Silvia Tacchi
- Istituto Officina dei Materiali-CNR, Basovizza SS-14, km 163.5, 34012 Trieste, Italy
| | - Cinzia Talamonti
- INFN (Istituto Nazionale di Fisica Nucleare) and Dipartimento di Fisica Scienze Biomediche Sperimentali e Cliniche “Mario Serio”, Viale Morgagni 50, 50135 Firenze, Italy
| | - Giovanni Verzellesi
- INFN (Istituto Nazionale di Fisica Nucleare), TIPFA (Trento Institute for Fundamental Physics and Applications), Via Sommarive 14, 38123 Trento, Italy
- Dipartimento di Scienze e Metodi dell’Ingegneria, Università di Modena e Reggio Emilia, Via Amendola 2, 42122 Reggio Emilia, Italy
| | - Nicolas Wyrsch
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Electrical and Microengineering (IME), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
| | - Nicola Zema
- Istituto di Struttura della Materia-CNR, Via Fosso del Cavaliere 100, 00133 Roma, Italy
| | - Maddalena Pedio
- INFN (Istituto Nazionale di Fisica Nucleare), Sez. di Perugia, Via Pascoli s.n.c., 06123 Perugia, Italy
- Istituto Officina dei Materiali-CNR, Via Pascoli s.n.c., 06123 Perugia, Italy
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12
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Zhong Y, Chen Z, Chen SD, Xu KJ, Hashimoto M, He Y, Uchida SI, Lu D, Mo SK, Shen ZX. Differentiated roles of Lifshitz transition on thermodynamics and superconductivity in La(2-)(x)Sr(x)CuO(4). Proc Natl Acad Sci U S A 2022; 119:e2204630119. [PMID: 35914123 DOI: 10.1073/pnas.2204630119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The effect of Lifshitz transition on thermodynamics and superconductivity in hole-doped cuprates has been heavily debated but remains an open question. In particular, an observed peak of electronic specific heat is proposed to originate from fluctuations of a putative quantum critical point p* (e.g., the termination of pseudogap at zero temperature), which is close to but distinguishable from the Lifshitz transition in overdoped La-based cuprates where the Fermi surface transforms from hole-like to electron-like. Here we report an in situ angle-resolved photoemission spectroscopy study of three-dimensional Fermi surfaces in La2-xSrxCuO4 thin films (x = 0.06 to 0.35). With accurate kz dispersion quantification, the said Lifshitz transition is determined to happen within a finite range around x = 0.21. Normal state electronic specific heat, calculated from spectroscopy-derived band parameters, reveals a doping-dependent profile with a maximum at x = 0.21 that agrees with previous thermodynamic microcalorimetry measurements. The account of the specific heat maximum by underlying band structures excludes the need for additionally dominant contribution from the quantum fluctuations at p*. A d-wave superconducting gap smoothly across the Lifshitz transition demonstrates the insensitivity of superconductivity to the dramatic density of states enhancement.
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13
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Lovász B, Sándor P, Kiss GZ, Bánhegyi B, Rácz P, Pápa Z, Budai J, Prietl C, Krenn JR, Dombi P. Nonadiabatic Nano-optical Tunneling of Photoelectrons in Plasmonic Near-Fields. Nano Lett 2022; 22:2303-2308. [PMID: 35240778 PMCID: PMC8949759 DOI: 10.1021/acs.nanolett.1c04651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/24/2022] [Indexed: 06/14/2023]
Abstract
Nonadiabatic nano-optical electron tunneling in the transition region between multiphoton-induced emission and adiabatic tunnel emission is explored in the near-field of plasmonic nanostructures. For Keldysh γ values between ∼1.3 and ∼2.2, measured photoemission spectra show strong-field recollision driven by the nanoscale near-field. At the same time, the photoemission yield shows an intensity scaling with a constant nonlinearity, which is characteristic for multiphoton-induced emission. Our observations in this transition region were well reproduced with the numerical solution of Schrödinger's equation, mimicking the nanoscale geometry of the field. This way, we determined the boundaries and nature of nonadiabatic tunneling photoemission, building on a key advantage of a nanoplasmonic system, namely, that high-field-driven recollision events and their signature in the photoemission spectrum can be observed more efficiently due to significant nanoplasmonic field enhancement factors.
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Affiliation(s)
- Béla Lovász
- Wigner
Research Centre for Physics, 1121 Budapest, Hungary
| | - Péter Sándor
- Wigner
Research Centre for Physics, 1121 Budapest, Hungary
| | | | | | - Péter Rácz
- Wigner
Research Centre for Physics, 1121 Budapest, Hungary
| | - Zsuzsanna Pápa
- Wigner
Research Centre for Physics, 1121 Budapest, Hungary
- ELI-ALPS
Research Institute, 6728 Szeged, Hungary
| | - Judit Budai
- ELI-ALPS
Research Institute, 6728 Szeged, Hungary
| | | | | | - Péter Dombi
- Wigner
Research Centre for Physics, 1121 Budapest, Hungary
- ELI-ALPS
Research Institute, 6728 Szeged, Hungary
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14
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Hamer M, Giampietri A, Kandyba V, Genuzio F, Menteş TO, Locatelli A, Gorbachev RV, Barinov A, Mucha-Kruczyński M. Moiré Superlattice Effects and Band Structure Evolution in Near-30-Degree Twisted Bilayer Graphene. ACS Nano 2022; 16:1954-1962. [PMID: 35073479 PMCID: PMC9007532 DOI: 10.1021/acsnano.1c06439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 01/20/2022] [Indexed: 06/01/2023]
Abstract
In stacks of two-dimensional crystals, mismatch of their lattice constants and misalignment of crystallographic axes lead to formation of moiré patterns. We show that moiré superlattice effects persist in twisted bilayer graphene (tBLG) with large twists and short moiré periods. Using angle-resolved photoemission, we observe dramatic changes in valence band topology across large regions of the Brillouin zone, including the vicinity of the saddle point at M and across 3 eV from the Dirac points. In this energy range, we resolve several moiré minibands and detect signatures of secondary Dirac points in the reconstructed dispersions. For twists θ > 21.8°, the low-energy minigaps are not due to cone anticrossing as is the case at smaller twist angles but rather due to moiré scattering of electrons in one graphene layer on the potential of the other which generates intervalley coupling. Our work demonstrates the robustness of the mechanisms which enable engineering of electronic dispersions of stacks of two-dimensional crystals by tuning the interface twist angles. It also shows that large-angle tBLG hosts electronic minigaps and van Hove singularities of different origin which, given recent progress in extreme doping of graphene, could be explored experimentally.
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Affiliation(s)
- Matthew
J. Hamer
- Department
of Physics, University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
| | | | | | | | | | | | - Roman V. Gorbachev
- Department
of Physics, University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
- Henry
Royce Institute, Oxford
Road, Manchester M13 9PL, United Kingdom
| | | | - Marcin Mucha-Kruczyński
- Department
of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
- Centre
for Nanoscience and Nanotechnology, University
of Bath, Claverton Down, Bath BA2
7AY, United Kingdom
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15
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Liu F, Guo L, DeFazio J, Pavlenko V, Yamamoto M, Moody NA, Yamaguchi H. Photoemission from Bialkali Photocathodes through an Atomically Thin Protection Layer. ACS Appl Mater Interfaces 2022; 14:1710-1717. [PMID: 34935342 DOI: 10.1021/acsami.1c19393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Photocathodes are essential components for various applications requiring photon-to-free-electron conversion, for example, high-sensitivity photodetectors and electron injectors for free-electron lasers. Alkali antimonide thin films are widely used as photocathode materials owing to their high quantum efficiency (QE) in the visible spectral range; however, their lifetime can be limited even in ultrahigh vacuum due to their high reactivity to residual gases and sensitivity to ion back-bombardment in these applications. An ambitious technical challenge is to extend the lifetime of bialkali photocathodes by coating them with suitable materials that can isolate the photocathode films from residual gases while still maintaining their highly emissive properties. We propose the use of graphene, an atomically thin two-dimensional material with gas impermeability, as a promising candidate for this purpose. Here, we report that high-quality bialkali antimonide can be grown on a two-layer (2L) suspended graphene substrate with a peak QE of 15%. More importantly, by comparing the photoemission through varying layers of graphene, we demonstrate that photoelectrons can transmit through few-layer graphene with a maximum QE of over 0.7% at 4.5 eV for 2L graphene, corresponding to a transmission efficiency of 5%. These results demonstrate important progress toward fully encapsulated bialkali photocathodes having both high QEs and long lifetimes using atomically thin protection layers.
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Affiliation(s)
- Fangze Liu
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, United States
- Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of Technology, Beijing 100081, China
| | - Lei Guo
- Nagoya University Synchrotron Radiation Research Center (NUSR), Furo, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Jeffrey DeFazio
- Photonis Defense Inc., 1000 New Holland Avenue, Lancaster, Pennsylvania 17601, United States
| | - Vitaly Pavlenko
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, United States
| | - Masahiro Yamamoto
- Accelerator Division 6, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Nathan A Moody
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, United States
| | - Hisato Yamaguchi
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, United States
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16
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Gruschwitz M, Ghosal C, Shen TH, Wolff S, Seyller T, Tegenkamp C. Surface Transport Properties of Pb-Intercalated Graphene. Materials (Basel) 2021; 14:ma14247706. [PMID: 34947298 PMCID: PMC8705698 DOI: 10.3390/ma14247706] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 11/26/2022]
Abstract
Intercalation experiments on epitaxial graphene are attracting a lot of attention at present as a tool to further boost the electronic properties of 2D graphene. In this work, we studied the intercalation of Pb using buffer layers on 6H-SiC(0001) by means of electron diffraction, scanning tunneling microscopy, photoelectron spectroscopy and in situ surface transport. Large-area intercalation of a few Pb monolayers succeeded via surface defects. The intercalated Pb forms a characteristic striped phase and leads to formation of almost charge neutral graphene in proximity to a Pb layer. The Pb intercalated layer consists of 2 ML and shows a strong structural corrugation. The epitaxial heterostructure provides an extremely high conductivity of σ=100 mS/□. However, at low temperatures (70 K), we found a metal-insulator transition that we assign to the formation of minigaps in epitaxial graphene, possibly induced by a static distortion of graphene following the corrugation of the interface layer.
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17
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Ohkochi T, Muro T, Ikenaga E, Togawa K, Yasui A, Kotsugi M, Oura M, Tanaka H. Multilateral surface analysis of the CeB 6 electron-gun cathode used at SACLA XFEL. J Synchrotron Radiat 2021; 28:1729-1736. [PMID: 34738926 DOI: 10.1107/s1600577521009656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
The CeB6(001) single crystal used as a cathode in a low-emittance electron gun and operated at the free-electron laser facility SACLA was investigated using cathode lens electron microscopy combined with X-ray spectroscopy at SPring-8 synchrotron radiation facility. Multilateral analysis using thermionic emission electron microscopy, low-energy electron microscopy, ultraviolet and X-ray photoemission electron microscopy and hard X-ray photoemission spectroscopy revealed that the thermionic electrons are emitted strongly and evenly from the CeB6 surface after pre-activation treatment (annealing at 1500°C for >1 h) and that the thermionic emission intensity as well as elemental composition vary between the central area and the edge of the old CeB6 surface.
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Affiliation(s)
- Takuo Ohkochi
- Japan Synchrotron Radiation Research Institute, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Takayuki Muro
- Japan Synchrotron Radiation Research Institute, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Eiji Ikenaga
- Japan Synchrotron Radiation Research Institute, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Kazuaki Togawa
- RIKEN SPring-8 Center, Kouto, Sayo, Hyogo 679-5148, Japan
| | - Akira Yasui
- Japan Synchrotron Radiation Research Institute, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Masato Kotsugi
- Japan Synchrotron Radiation Research Institute, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Masaki Oura
- RIKEN SPring-8 Center, Kouto, Sayo, Hyogo 679-5148, Japan
| | - Hitoshi Tanaka
- RIKEN SPring-8 Center, Kouto, Sayo, Hyogo 679-5148, Japan
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18
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Di Sabatino S, Koskelo J, Prodhon J, Berger JA, Caffarel M, Romaniello P. Photoemission Spectra from the Extended Koopman's Theorem, Revisited. Front Chem 2021; 9:746735. [PMID: 34692643 PMCID: PMC8531815 DOI: 10.3389/fchem.2021.746735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 09/15/2021] [Indexed: 11/13/2022] Open
Abstract
The Extended Koopman's Theorem (EKT) provides a straightforward way to compute charged excitations from any level of theory. In this work we make the link with the many-body effective energy theory (MEET) that we derived to calculate the spectral function, which is directly related to photoemission spectra. In particular, we show that at its lowest level of approximation the MEET removal and addition energies correspond to the so-called diagonal approximation of the EKT. Thanks to this link, the EKT and the MEET can benefit from mutual insight. In particular, one can readily extend the EKT to calculate the full spectral function, and choose a more optimal basis set for the MEET by solving the EKT secular equation. We illustrate these findings with the examples of the Hubbard dimer and bulk silicon.
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Affiliation(s)
- S Di Sabatino
- Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, UPS, Toulouse, France.,Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, Toulouse, France.,European Theoretical Spectroscopy Facility (ETSF), Toulouse, France
| | - J Koskelo
- Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, Toulouse, France.,European Theoretical Spectroscopy Facility (ETSF), Toulouse, France
| | - J Prodhon
- Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - J A Berger
- Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, UPS, Toulouse, France.,European Theoretical Spectroscopy Facility (ETSF), Toulouse, France
| | - M Caffarel
- Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - P Romaniello
- Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, Toulouse, France.,European Theoretical Spectroscopy Facility (ETSF), Toulouse, France
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19
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Strohbeen PJ, Manzo S, Saraswat V, Su K, Arnold MS, Kawasaki JK. Quantifying Mn Diffusion through Transferred versus Directly Grown Graphene Barriers. ACS Appl Mater Interfaces 2021; 13:42146-42153. [PMID: 34432424 DOI: 10.1021/acsami.1c10701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We quantify the mechanisms for manganese (Mn) diffusion through graphene in Mn/graphene/Ge (001) and Mn/graphene/GaAs (001) heterostructures for samples prepared by graphene layer transfer versus graphene growth directly on the semiconductor substrate. These heterostructures are important for applications in spintronics; however, challenges in synthesizing graphene directly on technologically important substrates such as GaAs necessitate layer transfer and annealing steps, which introduce defects into the graphene. In situ photoemission spectroscopy measurements reveal that Mn diffusion through graphene grown directly on a Ge (001) substrate is 1000 times lower than Mn diffusion into samples without graphene (Dgr,direct ∼ 4 × 10-18 cm2/s, Dno-gr ∼ 5 × 10-15 cm2/s at 500 °C). Transferred graphene on Ge suppresses the Mn in Ge diffusion by a factor of 10 compared to no graphene (Dgr,transfer ∼ 4 × 10-16 cm2/s). For both transferred and directly grown graphene, the low activation energy (Ea ∼ 0.1-0.5 eV) suggests that Mn diffusion through graphene occurs primarily at graphene defects. This is further confirmed as the diffusivity prefactor, D0, scales with the defect density of the graphene sheet. Similar diffusion barrier performance is found on GaAs substrates; however, it is not currently possible to grow graphene directly on GaAs. Our results highlight the importance of developing graphene growth directly on functional substrates to avoid the damage induced by layer transfer and annealing.
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Affiliation(s)
- Patrick J Strohbeen
- Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706, United States
| | - Sebastian Manzo
- Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706, United States
| | - Vivek Saraswat
- Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706, United States
| | - Katherine Su
- Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706, United States
| | - Michael S Arnold
- Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706, United States
| | - Jason K Kawasaki
- Materials Science and Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706, United States
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20
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Ali K, Fernández L, Kherelden MA, Makarova AA, Píš I, Bondino F, Lawrence J, de Oteyza DG, Usachov DY, Vyalikh DV, García de Abajo FJ, El‐Fattah ZMA, Ortega JE, Schiller F. Atomically-Precise Texturing of Hexagonal Boron Nitride Nanostripes. Adv Sci (Weinh) 2021; 8:e2101455. [PMID: 34293238 PMCID: PMC8425884 DOI: 10.1002/advs.202101455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/25/2021] [Indexed: 06/13/2023]
Abstract
Monolayer hexagonal boron nitride (hBN) is attracting considerable attention because of its potential applications in areas such as nano- and opto-electronics, quantum optics and nanomagnetism. However, the implementation of such functional hBN demands precise lateral nanostructuration and integration with other two-dimensional materials, and hence, novel routes of synthesis beyond exfoliation. Here, a disruptive approach is demonstrated, namely, imprinting the lateral pattern of an atomically stepped one-dimensional template into a hBN monolayer. Specifically, hBN is epitaxially grown on vicinal Rhodium (Rh) surfaces using a Rh curved crystal for a systematic exploration, which produces a periodically textured, nanostriped hBN carpet that coats Rh(111)-oriented terraces and lattice-matched Rh(337) facets with tunable width. The electronic structure reveals a nanoscale periodic modulation of the hBN atomic potential that leads to an effective lateral semiconductor multi-stripe. The potential of such atomically thin hBN heterostructure for future applications is discussed.
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Affiliation(s)
- Khadiza Ali
- Centro de Física de Materiales CSIC/UPV‐EHU‐Materials Physics CenterSan SebastiánE‐20018Spain
| | - Laura Fernández
- Centro de Física de Materiales CSIC/UPV‐EHU‐Materials Physics CenterSan SebastiánE‐20018Spain
- Universidad del País VascoDpto. Física AplicadaSan SebastiánE‐20018Spain
| | | | | | - Igor Píš
- IOM‐CNRLaboratorio TASCTriesteI‐34149Italy
- Elettra ‐ Sincrotrone Trieste S.C.p.A.TriesteI‐34149Italy
| | | | - James Lawrence
- Donostia International Physics CenterSan SebastiánE‐20018Spain
| | | | | | - Denis V. Vyalikh
- Donostia International Physics CenterSan SebastiánE‐20018Spain
- IkerbasqueBasque Foundation for ScienceBasque CountryBilbao48013Spain
| | - F. Javier García de Abajo
- ICFO‐Institut de Ciencies FotoniquesThe Barcelona Institute of Science and TechnologyBarcelona08860Spain
- ICREA‐Institució Catalana de Recerca i Estudis AvançatsPasseig Lluís Companys 23Barcelona08010Spain
| | | | - J. Enrique Ortega
- Centro de Física de Materiales CSIC/UPV‐EHU‐Materials Physics CenterSan SebastiánE‐20018Spain
- Universidad del País VascoDpto. Física AplicadaSan SebastiánE‐20018Spain
- Donostia International Physics CenterSan SebastiánE‐20018Spain
| | - Frederik Schiller
- Centro de Física de Materiales CSIC/UPV‐EHU‐Materials Physics CenterSan SebastiánE‐20018Spain
- Donostia International Physics CenterSan SebastiánE‐20018Spain
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21
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Sygletou M, Benedetti S, Ferrera M, Pierantozzi GM, Cucini R, Della Valle G, Carrara P, De Vita A, di Bona A, Torelli P, Catone D, Panaccione G, Canepa M, Bisio F. Quantitative Ultrafast Electron-Temperature Dynamics in Photo-Excited Au Nanoparticles. Small 2021; 17:e2100050. [PMID: 34061425 DOI: 10.1002/smll.202100050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/16/2021] [Indexed: 06/12/2023]
Abstract
The femtosecond evolution of the electronic temperature of laser-excited gold nanoparticles is measured, by means of ultrafast time-resolved photoemission spectroscopy induced by extreme-ultraviolet radiation pulses. The temperature of the electron gas is deduced by recording and fitting high-resolution photo emission spectra around the Fermi edge of gold nanoparticles providing a direct, unambiguous picture of the ultrafast electron-gas dynamics. These results will be instrumental to the refinement of existing models of femtosecond processes in laterally-confined and bulk condensed-matter systems, and for understanding more deeply the role of hot electrons in technological applications.
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Affiliation(s)
- Maria Sygletou
- OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146, Genova, Italy
| | | | - Marzia Ferrera
- OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146, Genova, Italy
| | - Gian Marco Pierantozzi
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste, I-34149, Italy
| | - Riccardo Cucini
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste, I-34149, Italy
| | - Giuseppe Della Valle
- Dipartimento di Fisica, IFN-CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano, Italy
| | - Pietro Carrara
- Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, Milano, Italy
| | - Alessandro De Vita
- Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, Milano, Italy
| | | | - Piero Torelli
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste, I-34149, Italy
| | - Daniele Catone
- Istituto di Struttura della Materia - CNR (ISM-CNR), EuroFEL Support Laboratory (EFSL), Via del Fosso del Cavaliere, 100, I-00133, Rome, Italy
| | - Giancarlo Panaccione
- Istituto Officina dei Materiali-CNR, Laboratorio TASC, Area Science Park, S.S. 14, Km 163.5, Trieste, I-34149, Italy
| | - Maurizio Canepa
- OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146, Genova, Italy
| | - Francesco Bisio
- CNR-SPIN Istituto Superconduttori Materiali Innovativi e Dispositivi, C.so Perrone 24, I-16152, Genova, Italy
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22
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Okamura K. Spin-dependent electron-radiation interaction. J Phys Condens Matter 2021; 33:285501. [PMID: 34103459 DOI: 10.1088/1361-648x/abfc6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/28/2021] [Indexed: 06/12/2023]
Abstract
Spin-dependent electron-radiation interaction is derived from the Foldy-Wouthuysen transformations of the Dirac equation. A spin magnetic moment term is identified both with spin-preserving and spin-flipping transitions and inspected for atoms and condensed matter specifically of GaAs on the basis of first-principles calculation. The connections to spin relaxation and spin-resolved photoemission are also presented.
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Affiliation(s)
- Koshi Okamura
- Ronin Institute, Montclair, NJ 07043, United States of America
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23
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Gunjo Y, Kamebuchi H, Tsuruta R, Iwashita M, Takahashi K, Takeuchi R, Kanai K, Koganezawa T, Mase K, Tadokoro M, Nakayama Y. Interface Structures and Electronic States of Epitaxial Tetraazanaphthacene on Single-Crystal Pentacene. Materials (Basel) 2021; 14:ma14051088. [PMID: 33652700 PMCID: PMC7956789 DOI: 10.3390/ma14051088] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 02/19/2021] [Accepted: 02/19/2021] [Indexed: 02/04/2023]
Abstract
The structural and electronic properties of interfaces composed of donor and acceptor molecules play important roles in the development of organic opto-electronic devices. Epitaxial growth of organic semiconductor molecules offers a possibility to control the interfacial structures and to explore precise properties at the intermolecular contacts. 5,6,11,12-tetraazanaphthacene (TANC) is an acceptor molecule with a molecular structure similar to that of pentacene, a representative donor material, and thus, good compatibility with pentacene is expected. In this study, the physicochemical properties of the molecular interface between TANC and pentacene single crystal (PnSC) substrates were analyzed by atomic force microscopy, grazing-incidence X-ray diffraction (GIXD), and photoelectron spectroscopy. GIXD revealed that TANC molecules assemble into epitaxial overlayers of the (010) oriented crystallites by aligning an axis where the side edges of the molecules face each other along the [1¯10] direction of the PnSC. No apparent interface dipole was found, and the energy level offset between the highest occupied molecular orbitals of TANC and the PnSC was determined to be 1.75 eV, which led to a charge transfer gap width of 0.7 eV at the interface.
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Affiliation(s)
- Yuki Gunjo
- Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; (Y.G.); (R.T.); (M.I.); (K.T.); (R.T.)
| | - Hajime Kamebuchi
- Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan; (H.K.); (M.T.)
| | - Ryohei Tsuruta
- Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; (Y.G.); (R.T.); (M.I.); (K.T.); (R.T.)
| | - Masaki Iwashita
- Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; (Y.G.); (R.T.); (M.I.); (K.T.); (R.T.)
| | - Kana Takahashi
- Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; (Y.G.); (R.T.); (M.I.); (K.T.); (R.T.)
| | - Riku Takeuchi
- Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; (Y.G.); (R.T.); (M.I.); (K.T.); (R.T.)
| | - Kaname Kanai
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan;
- Division of Colloid and Interface Science, Research Institute for Science & Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Tomoyuki Koganezawa
- Industrial Application Division, Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan;
| | - Kazuhiko Mase
- Institute for Materials Structure Science, High Energy Accelerator Research Organization (KEK) and SOKENDAI, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan;
| | - Makoto Tadokoro
- Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan; (H.K.); (M.T.)
- Division of Colloid and Interface Science, Research Institute for Science & Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Yasuo Nakayama
- Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; (Y.G.); (R.T.); (M.I.); (K.T.); (R.T.)
- Division of Colloid and Interface Science, Research Institute for Science & Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
- Correspondence: ; Tel.: +81-04-7124-1501 (ext. 3601)
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24
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Möllers PV, Ulku S, Jayarathna D, Tassinari F, Nürenberg D, Naaman R, Achim C, Zacharias H. Spin-selective electron transmission through self-assembled monolayers of double-stranded peptide nucleic acid. Chirality 2021; 33:93-102. [PMID: 33400337 DOI: 10.1002/chir.23290] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/06/2020] [Accepted: 12/01/2020] [Indexed: 12/19/2022]
Abstract
Monolayers of chiral molecules can preferentially transmit electrons with a specific spin orientation, introducing chiral molecules as efficient spin filters. This phenomenon is established as chirality-induced spin selectivity (CISS) and was demonstrated directly for the first time in self-assembled monolayers (SAMs) of double-stranded DNA (dsDNA)1 . Here, we discuss SAMs of double-stranded peptide nucleic acid (dsPNA) as a system which allows for systematic investigations of the influence of various molecular properties on CISS. In photoemission studies, SAMs of chiral, γ-modified PNA show significant spin filtering of up to P = (24.4 ± 4.3)% spin polarization. The polarization values found in PNA lacking chiral monomers are considerably lower at about P = 12%. The results confirm that the preferred spin orientation is directly linked to the molecular handedness and indicate that the spin filtering capacity of the dsPNA helices might be enhanced by introduction of chiral centers in the constituting peptide monomers.
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Affiliation(s)
- Paul Valerian Möllers
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Selma Ulku
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Dilhara Jayarathna
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Francesco Tassinari
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Daniel Nürenberg
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Ron Naaman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Catalina Achim
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Helmut Zacharias
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Münster, Germany
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25
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Elmers HJ, Chernov SV, D'Souza SW, Bommanaboyena SP, Bodnar SY, Medjanik K, Babenkov S, Fedchenko O, Vasilyev D, Agustsson SY, Schlueter C, Gloskovskii A, Matveyev Y, Strocov VN, Skourski Y, Šmejkal L, Sinova J, Minár J, Kläui M, Schönhense G, Jourdan M. Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn 2Au. ACS Nano 2020; 14:17554-17564. [PMID: 33236903 DOI: 10.1021/acsnano.0c08215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Néel vector indicating the direction of the staggered magnetization. Pulsed magnetic fields of 60 T were used to orient the sublattice magnetizations of capped epitaxial Mn2Au(001) thin films perpendicular to the applied field direction by a spin-flop transition. The electronic structure and its corresponding changes were investigated by angular-resolved photoemission spectroscopy with photon energies in the vacuum-ultraviolet, soft, and hard X-ray range. The results reveal an energetic rearrangement of conduction electrons propagating perpendicular to the Néel vector. They confirm previous predictions on the origin of the Néel spin-orbit torque and anisotropic magnetoresistance in Mn2Au and reflect the combined antiferromagnetic and spin-orbit interaction in this compound leading to inversion symmetry breaking.
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Affiliation(s)
- H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S V Chernov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S W D'Souza
- New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - S P Bommanaboyena
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Yu Bodnar
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Babenkov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Y Agustsson
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - A Gloskovskii
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Yu Matveyev
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - Y Skourski
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - L Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - J Sinova
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - J Minár
- New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - M Kläui
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - M Jourdan
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
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26
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Haags A, Reichmann A, Fan Q, Egger L, Kirschner H, Naumann T, Werner S, Vollgraff T, Sundermeyer J, Eschmann L, Yang X, Brandstetter D, Bocquet FC, Koller G, Gottwald A, Richter M, Ramsey MG, Rohlfing M, Puschnig P, Gottfried JM, Soubatch S, Tautz FS. Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization. ACS Nano 2020; 14:15766-15775. [PMID: 33186031 PMCID: PMC7690051 DOI: 10.1021/acsnano.0c06798] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 11/03/2020] [Indexed: 05/08/2023]
Abstract
We revisit the question of kekulene's aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene's highest occupied molecular orbital by photoemission tomography. In agreement with a recent aromaticity assessment of kekulene based solely on C-C bond lengths, we conclude that the π-conjugation of kekulene is better described by the Clar model rather than a superaromatic model. Thus, by exploiting the capabilities of photoemission tomography, we shed light on the question which consequences aromaticity holds for the frontier electronic structure of a π-conjugated molecule.
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Affiliation(s)
- Anja Haags
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals of Future Information
Technology, 52425 Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Alexander Reichmann
- Institut
für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - Qitang Fan
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Larissa Egger
- Institut
für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - Hans Kirschner
- Physikalisch-Technische
Bundesanstalt (PTB), 10587 Berlin, Germany
| | - Tim Naumann
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Simon Werner
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Tobias Vollgraff
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Jörg Sundermeyer
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Lukas Eschmann
- Institut
für Festkörpertheorie, Westfälische
Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Xiaosheng Yang
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals of Future Information
Technology, 52425 Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Dominik Brandstetter
- Institut
für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - François C. Bocquet
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals of Future Information
Technology, 52425 Jülich, Germany
| | - Georg Koller
- Institut
für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | | | - Mathias Richter
- Physikalisch-Technische
Bundesanstalt (PTB), 10587 Berlin, Germany
| | - Michael G. Ramsey
- Institut
für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - Michael Rohlfing
- Institut
für Festkörpertheorie, Westfälische
Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Peter Puschnig
- Institut
für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - J. Michael Gottfried
- Fachbereich
Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Serguei Soubatch
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals of Future Information
Technology, 52425 Jülich, Germany
| | - F. Stefan Tautz
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals of Future Information
Technology, 52425 Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074 Aachen, Germany
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27
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Haags A, Reichmann A, Fan Q, Egger L, Kirschner H, Naumann T, Werner S, Vollgraff T, Sundermeyer J, Eschmann L, Yang X, Brandstetter D, Bocquet FC, Koller G, Gottwald A, Richter M, Ramsey MG, Rohlfing M, Puschnig P, Gottfried JM, Soubatch S, Tautz FS. Kekulene: On-Surface Synthesis, Orbital Structure, and Aromatic Stabilization. ACS Nano 2020; 14:15766-15775. [PMID: 33186031 DOI: 10.26434/chemrxiv.12771254.v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We revisit the question of kekulene's aromaticity by focusing on the electronic structure of its frontier orbitals as determined by angle-resolved photoemission spectroscopy. To this end, we have developed a specially designed precursor, 1,4,7(2,7)-triphenanthrenacyclononaphane-2,5,8-triene, which allows us to prepare sufficient quantities of kekulene of high purity directly on a Cu(111) surface, as confirmed by scanning tunneling microscopy. Supported by density functional calculations, we determine the orbital structure of kekulene's highest occupied molecular orbital by photoemission tomography. In agreement with a recent aromaticity assessment of kekulene based solely on C-C bond lengths, we conclude that the π-conjugation of kekulene is better described by the Clar model rather than a superaromatic model. Thus, by exploiting the capabilities of photoemission tomography, we shed light on the question which consequences aromaticity holds for the frontier electronic structure of a π-conjugated molecule.
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Affiliation(s)
- Anja Haags
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Alexander Reichmann
- Institut für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - Qitang Fan
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Larissa Egger
- Institut für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - Hans Kirschner
- Physikalisch-Technische Bundesanstalt (PTB), 10587 Berlin, Germany
| | - Tim Naumann
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Simon Werner
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Tobias Vollgraff
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Jörg Sundermeyer
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Lukas Eschmann
- Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Xiaosheng Yang
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, 52074 Aachen, Germany
| | - Dominik Brandstetter
- Institut für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - François C Bocquet
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - Georg Koller
- Institut für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | | | - Mathias Richter
- Physikalisch-Technische Bundesanstalt (PTB), 10587 Berlin, Germany
| | - Michael G Ramsey
- Institut für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - Michael Rohlfing
- Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Peter Puschnig
- Institut für Physik, Karl-Franzens-Universität Graz, NAWI Graz, 8010 Graz, Austria
| | - J Michael Gottfried
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Serguei Soubatch
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
| | - F Stefan Tautz
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
- Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425 Jülich, Germany
- Experimentalphysik IV A, RWTH Aachen University, 52074 Aachen, Germany
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28
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Aprojanz J, Rosenzweig P, Nguyen TTN, Karakachian H, Küster K, Starke U, Lukosius M, Lippert G, Sinterhauf A, Wenderoth M, Zakharov AA, Tegenkamp C. High-Mobility Epitaxial Graphene on Ge/Si(100) Substrates. ACS Appl Mater Interfaces 2020; 12:43065-43072. [PMID: 32865383 DOI: 10.1021/acsami.0c10725] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Graphene was shown to reveal intriguing properties of its relativistic two-dimensional electron gas; however, its implementation to microelectronic applications is missing to date. In this work, we present a comprehensive study of epitaxial graphene on technologically relevant and in a standard CMOS process achievable Ge(100) epilayers grown on Si(100) substrates. Crystalline graphene monolayer structures were grown by means of chemical vapor deposition (CVD). Using angle-resolved photoemission spectroscopy and in situ surface transport measurements, we demonstrate their metallic character both in momentum and real space. Despite numerous crystalline imperfections, e.g., grain boundaries and strong corrugation, as compared to epitaxial graphene on SiC(0001), charge carrier mobilities of 1 × 104 cm2/Vs were obtained at room temperature, which is a result of the quasi-charge neutrality within the graphene monolayers on germanium and not dependent on the presence of an interface oxide. The interface roughness due to the facet structure of the Ge(100) epilayer, formed during the CVD growth of graphene, can be reduced via subsequent in situ annealing up to 850 °C coming along with an increase in the mobility by 30%. The formation of a Ge(100)-(2 × 1) structure demonstrates the weak interaction and effective delamination of graphene from the Ge/Si(100) substrate.
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Affiliation(s)
- J Aprojanz
- Institut für Physik, Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - Ph Rosenzweig
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - T T Nhung Nguyen
- Institut für Physik, Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - H Karakachian
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - K Küster
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - U Starke
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - M Lukosius
- Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, Frankfurt (Oder) 15236, Germany
| | - G Lippert
- Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, Frankfurt (Oder) 15236, Germany
| | - A Sinterhauf
- IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - M Wenderoth
- IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - A A Zakharov
- MAX IV Laboratory and Lund University, Lund 22100, Sweden
| | - C Tegenkamp
- Institut für Physik, Technische Universität Chemnitz, Chemnitz 09126, Germany
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29
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Dong B, Afanasev A, Johnson R, Zaghloul M. Enhancement of Photoemission on p-Type GaAs Using Surface Acoustic Waves. Sensors (Basel) 2020; 20:E2419. [PMID: 32344596 PMCID: PMC7219497 DOI: 10.3390/s20082419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/19/2020] [Accepted: 04/22/2020] [Indexed: 11/16/2022]
Abstract
We demonstrate that photoemission properties of p-type GaAs can be altered by surface acoustic waves (SAWs) generated on the GaAs surface due to dynamical piezoelectric fields of SAWs. Multiphysics simulations indicate that charge-carrier recombination is greatly reduced, and electron effective lifetime in p-doped GaAs may increase by a factor of 10× to 20×. It implies a significant increase, by a factor of 2× to 3×, of quantum efficiency (QE) for GaAs photoemission applications, like GaAs photocathodes. Conditions of different SAW wavelengths, swept SAW intensities, and varied incident photon energies were investigated. Essential steps in SAW device fabrication on a GaAs substrate are demonstrated, including deposition of an additional layer of ZnO for piezoelectric effect enhancement, measurements of current-voltage (I-V) characteristics of the SAW device, and ability to survive high-temperature annealing. Results obtained and reported in this study provide the potential and basis for future studies on building SAW-enhanced photocathodes, as well as other GaAs photoelectric applications.
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Affiliation(s)
- Boqun Dong
- School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA
| | - Andrei Afanasev
- Department of Physics, The George Washington University, Washington, DC 20052, USA
| | | | - Mona Zaghloul
- School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA
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30
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Belser A, Greulich K, Grüninger P, Bettinger HF, Peisert H, Chassé T. Visualization of the Borazine Core of B 3N 3-Doped Nanographene by STM. ACS Appl Mater Interfaces 2020; 12:19218-19225. [PMID: 32223213 DOI: 10.1021/acsami.0c02324] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electronic interface properties and the initial growth of hexa-peri-hexabenzocoronene with a borazine core (BN-HBC) on Au(111) have been studied by using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM). A weak, but non-negligible, interaction between BN-HBC and Au(111) was found at the interface. Both hexa-peri-hexabenzocoronene (HBC) and BN-HBC molecules form well-defined monolayers. The different contrast in STM images of HBC and BN-HBC at different tunneling voltages with submolecular resolution can be ascribed to differences in the local density of states (LDOS). At positive and negative tunneling voltages, STM images reproduce the distribution of the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) as determined by density functional theory (DFT) calculations very well.
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Affiliation(s)
- Axel Belser
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Katharina Greulich
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Peter Grüninger
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Holger F Bettinger
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+) at the University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Thomas Chassé
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+) at the University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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31
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Wang B, Yang S, Wang Y, Ahsan R, He X, Kim Y, Htoon H, Kapadia R, John DD, Thibeault B, Doorn SK, Cronin SB. Auger Suppression of Incandescence in Individual Suspended Carbon Nanotube pn-Junctions. ACS Appl Mater Interfaces 2020; 12:11907-11912. [PMID: 32083460 DOI: 10.1021/acsami.9b17519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
There are various mechanisms of light emission in carbon nanotubes (CNTs), which give rise to a wide range of spectral characteristics that provide important information. Here we report suppression of incandescence via Auger recombination in suspended carbon nanotube pn-junctions generated from dual-gate CNT field-effect transistor (FET) devices. By applying equal and opposite voltages to the gate electrodes (i.e., Vg1 = -Vg2), we create a pn-junction within the CNT. Under these gating conditions, we observe a sharp peak in the incandescence intensity around zero applied gate voltage, where the intrinsic region has the largest spatial extent. Here, the emission occurs under high electrical power densities of around 0.1 MW/cm2 (or 6 μW) and arises from thermal emission at elevated temperatures above 800 K (i.e., incandescence). It is somewhat surprising that this thermal emission intensity is so sensitive to the gating conditions, and we observe a 1000-fold suppression of light emission between Vg1 = 0 and 15 V, over a range in which the electrical power dissipated in the nanotube is roughly constant. This behavior is understood on the basis of Auger recombination, which suppresses light emission by the excitation of free carriers. Based on the calculated carrier density and band profiles, the length of the intrinsic region drops by a factor of 7-25× over the range from |Vg| = 0 to 15 V. We, therefore, conclude that the light emission intensity is significantly dependent on the free carrier density profile and the size of the intrinsic region in these CNT devices.
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Affiliation(s)
| | | | | | | | - Xiaowei He
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Younghee Kim
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Han Htoon
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | | | - Demis D John
- Nanotech, Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Brian Thibeault
- Nanotech, Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Stephen K Doorn
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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32
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Hartmann C, Gupta S, Bendikov T, Kozina X, Kunze T, Félix R, Hodes G, Wilks RG, Cahen D, Bär M. Impact of SnF 2 Addition on the Chemical and Electronic Surface Structure of CsSnBr 3. ACS Appl Mater Interfaces 2020; 12:12353-12361. [PMID: 32045207 PMCID: PMC7307835 DOI: 10.1021/acsami.9b22967] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report on the chemical and electronic structure of cesium tin bromide (CsSnBr3) and how it is impacted by the addition of 20 mol % tin fluoride (SnF2) to the precursor solution, using both surface-sensitive lab-based soft X-ray photoelectron spectroscopy (XPS) and near-surface bulk-sensitive synchrotron-based hard XPS (HAXPES). To determine the reproducibility and reliability of conclusions, several (nominally identically prepared) sample sets were investigated. The effects of deposition reproducibility, handling, and transport are found to cause significant changes in the measured properties of the films. Variations in the HAXPES-derived compositions between individual sample sets were observed, but in general, they confirm that the addition of 20 mol % SnF2 improves coverage of the titanium dioxide substrate by CsSnBr3 and decreases the oxidation of SnII to SnIV while also suppressing formation of secondary Br and Cs species. Furthermore, the (surface) composition is found to be Cs-deficient and Sn-rich compared to the nominal stoichiometry. The valence band (VB) shows a SnF2-induced redistribution of Sn 5s-derived density of states, reflecting the changing SnII/SnIV ratio. Notwithstanding some variability in the data, we conclude that SnF2 addition decreases the energy difference between the VB maximum of CsSnBr3 and the Fermi level, which we explain by defect chemistry considerations.
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Affiliation(s)
- Claudia Hartmann
- Interface
Design, Helmholtz-Zentrum Berlin für
Materialien und Energie GmbH (HZB), 14109 Berlin, Germany
| | - Satyajit Gupta
- Department
of Materials & Interfaces, Weizmann
Institute of Science (WIS), 7610001 Rehovot, Israel
- Department
of Chemistry, Indian Institute of Technology
Bhilai, GEC Campus, Chhattisgarh 492015, India
| | - Tatyana Bendikov
- Chemical
Research Support Unit, Weizmann Institute
of Science (WIS), Rehovot 7610001, Israel
| | - Xeniya Kozina
- Interface
Design, Helmholtz-Zentrum Berlin für
Materialien und Energie GmbH (HZB), 14109 Berlin, Germany
| | - Thomas Kunze
- Interface
Design, Helmholtz-Zentrum Berlin für
Materialien und Energie GmbH (HZB), 14109 Berlin, Germany
| | - Roberto Félix
- Interface
Design, Helmholtz-Zentrum Berlin für
Materialien und Energie GmbH (HZB), 14109 Berlin, Germany
| | - Gary Hodes
- Department
of Materials & Interfaces, Weizmann
Institute of Science (WIS), 7610001 Rehovot, Israel
- E-mail: (G.H.)
| | - Regan G. Wilks
- Interface
Design, Helmholtz-Zentrum Berlin für
Materialien und Energie GmbH (HZB), 14109 Berlin, Germany
- Energy
Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
(HZB), 12489 Berlin, Germany
| | - David Cahen
- Department
of Materials & Interfaces, Weizmann
Institute of Science (WIS), 7610001 Rehovot, Israel
- E-mail: (D.C.)
| | - Marcus Bär
- Interface
Design, Helmholtz-Zentrum Berlin für
Materialien und Energie GmbH (HZB), 14109 Berlin, Germany
- Energy
Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
(HZB), 12489 Berlin, Germany
- Helmholtz-Institute
Erlangen-Nürnberg for Renewable Energy (HI ERN), Helmholtz-Zentrum Berlin für Materialien und
Energie GmbH (HZB), 12489 Berlin, Germany
- Department
of Chemistry & Pharmacy, Friedrich-Alexander-Universität
Erlangen-Nürnberg, 91058 Erlangen, Germany
- E-mail: (M.B.)
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33
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Herrmann H, Hlawenka P, Siemensmeyer K, Weschke E, Sánchez-Barriga J, Varykhalov A, Shitsevalova NY, Dukhnenko AV, Filipov VB, Gabáni S, Flachbart K, Rader O, Sterrer M, Rienks EDL. Contrast Reversal in Scanning Tunneling Microscopy and Its Implications for the Topological Classification of SmB 6. Adv Mater 2020; 32:e1906725. [PMID: 31997471 DOI: 10.1002/adma.201906725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/06/2019] [Indexed: 06/10/2023]
Abstract
SmB6 has recently attracted considerable interest as a candidate for the first strongly correlated topological insulator. Such materials promise entirely new properties such as correlation-enhanced bulk bandgaps or a Fermi surface from spin excitations. Whether SmB6 and its surface states are topological or trivial is still heavily disputed however, and a solution is hindered by major disagreement between angle-resolved photoemission (ARPES) and scanning tunneling microscopy (STM) results. Here, a combined ARPES and STM experiment is conducted. It is discovered that the STM contrast strongly depends on the bias voltage and reverses its sign beyond 1 V. It is shown that the understanding of this contrast reversal is the clue to resolving the discrepancy between ARPES and STM results. In particular, the scanning tunneling spectra reflect a low-energy electronic structure at the surface, which supports a trivial origin of the surface states and the surface metallicity of SmB6 .
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Affiliation(s)
- Hannes Herrmann
- Institut für Physik, Karl-Franzens-Universität Graz, Universitätsplatz 5, 8010, Graz, Austria
| | - Peter Hlawenka
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Konrad Siemensmeyer
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Eugen Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Jaime Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Andrei Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Natalya Y Shitsevalova
- Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Krzhyzhanovsky str. 3, 03142, Kiev, Ukraine
| | - Anatoliy V Dukhnenko
- Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Krzhyzhanovsky str. 3, 03142, Kiev, Ukraine
| | - Volodymyr B Filipov
- Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Krzhyzhanovsky str. 3, 03142, Kiev, Ukraine
| | - Slavomir Gabáni
- Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001, Košice, Slovakia
| | - Karol Flachbart
- Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001, Košice, Slovakia
| | - Oliver Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Martin Sterrer
- Institut für Physik, Karl-Franzens-Universität Graz, Universitätsplatz 5, 8010, Graz, Austria
| | - Emile D L Rienks
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489, Berlin, Germany
- Institut für Festkörperphysik, Technische Universität Dresden, 01062, Dresden, Germany
- Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
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34
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Karstens R, Glaser M, Belser A, Balle D, Polek M, Ovsyannikov R, Giangrisostomi E, Chassé T, Peisert H. FePc and FePcF 16 on Rutile TiO 2(110) and (100): Influence of the Substrate Preparation on the Interaction Strength. Molecules 2019; 24:E4579. [PMID: 31847299 PMCID: PMC6943671 DOI: 10.3390/molecules24244579] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 11/30/2022] Open
Abstract
Interface properties of iron phthalocyanine (FePc) and perfluorinated iron phthalocyanine (FePcF16) on rutile TiO2(100) and TiO2(110) surfaces were studied using X-ray photoemission spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and low-energy electron diffraction (LEED). It is demonstrated that the interaction strength at the interfaces is considerably affected by the detailed preparation procedure. Weak interactions were observed for all studied interfaces between FePc or FePcF16 and rutile, as long as the substrate was exposed to oxygen during the annealing steps of the preparation procedure. The absence of oxygen in the last annealing step only had almost no influence on interface properties. In contrast, repeated substrate cleaning cycles performed in the absence of oxygen resulted in a more reactive, defect-rich substrate surface. On such reactive surfaces, stronger interactions were observed, including the cleavage of some C-F bonds of FePcF16.
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Affiliation(s)
- Reimer Karstens
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
| | - Mathias Glaser
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
| | - Axel Belser
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
| | - David Balle
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
| | - Małgorzata Polek
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
| | - Ruslan Ovsyannikov
- Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany; (R.O.); (E.G.)
| | - Erika Giangrisostomi
- Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany; (R.O.); (E.G.)
| | - Thomas Chassé
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+) at the University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; (R.K.); (M.G.); (A.B.); (D.B.); (M.P.); (T.C.)
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35
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Whittles TJ, Veal TD, Savory CN, Yates PJ, Murgatroyd PAE, Gibbon JT, Birkett M, Potter RJ, Major JD, Durose K, Scanlon DO, Dhanak VR. Band Alignments, Band Gap, Core Levels, and Valence Band States in Cu 3BiS 3 for Photovoltaics. ACS Appl Mater Interfaces 2019; 11:27033-27047. [PMID: 31276370 DOI: 10.1021/acsami.9b04268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The earth-abundant semiconductor Cu3BiS3 (CBS) exhibits promising photovoltaic properties and is often considered analogous to the solar absorbers copper indium gallium diselenide (CIGS) and copper zinc tin sulfide (CZTS) despite few device reports. The extent to which this is justifiable is explored via a thorough X-ray photoemission spectroscopy (XPS) analysis: spanning core levels, ionization potential, work function, surface contamination, cleaning, band alignment, and valence-band density of states. The XPS analysis overcomes and addresses the shortcomings of prior XPS studies of this material. Temperature-dependent absorption spectra determine a 1.2 eV direct band gap at room temperature; the widely reported 1.4-1.5 eV band gap is attributed to weak transitions from the low density of states of the topmost valence band previously being undetected. Density functional theory HSE06 + SOC calculations determine the band structure, optical transitions, and well-fitted absorption and Raman spectra. Valence band XPS spectra and model calculations find the CBS bonding to be superficially similar to CIGS and CZTS, but the Bi3+ cations (and formally occupied Bi 6s orbital) have fundamental impacts: giving a low ionization potential (4.98 eV), suggesting that the CdS window layer favored for CIGS and CZTS gives detrimental band alignment and should be rejected in favor of a better aligned material in order for CBS devices to progress.
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Affiliation(s)
- Thomas J Whittles
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - Tim D Veal
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - Christopher N Savory
- Department of Chemistry , University College London , Christopher Ingold Building , London WC1H 0AJ , U.K
- Thomas Young Centre , University College London , Gower Street , London WC1E 6BT , U.K
| | - Peter J Yates
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - Philip A E Murgatroyd
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - James T Gibbon
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - Max Birkett
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - Richard J Potter
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering , University of Liverpool , Liverpool , L69 3GH , U.K
| | - Jonathan D Major
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - Ken Durose
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
| | - David O Scanlon
- Department of Chemistry , University College London , Christopher Ingold Building , London WC1H 0AJ , U.K
- Diamond Light Source Limited , Diamond House, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 0DE , U.K
- Thomas Young Centre , University College London , Gower Street , London WC1E 6BT , U.K
| | - Vinod R Dhanak
- Department of Physics and Stephenson Institute for Renewable Energy , University of Liverpool , Liverpool , L69 7ZF , U.K
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36
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Green ME, Bas DA, Yao HY, Gengler JJ, Headrick RJ, Back TC, Urbas AM, Pasquali M, Kono J, Her TH. Bright and Ultrafast Photoelectron Emission from Aligned Single-Wall Carbon Nanotubes through Multiphoton Exciton Resonance. Nano Lett 2019; 19:158-164. [PMID: 30484322 DOI: 10.1021/acs.nanolett.8b03564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ultrashort bunches of electrons, emitted from solid surfaces through excitation by ultrashort laser pulses, are an essential ingredient in advanced X-ray sources, and ultrafast electron diffraction and spectroscopy. Multiphoton photoemission using a noble metal as the photocathode material is typically used but more brightness is desired. Artificially structured metal photocathodes have been shown to enhance optical absorption via surface plasmon resonance but such an approach severely reduces the damage threshold in addition to requiring state-of-the-art facilities for photocathode fabrication. Here, we report ultrafast photoelectron emission from sidewalls of aligned single-wall carbon nanotubes. We utilized strong exciton resonances inherent in this prototypical one-dimensional material, and its excellent thermal conductivity and mechanical rigidity leading to a high damage threshold. We obtained unambiguous evidence for resonance-enhanced multiphoton photoemission processes with definite power-law behaviors. In addition, we observed strong polarization dependence and ultrashort photoelectron response time, both of which can be quantitatively explained by our model. These results firmly establish aligned single-wall carbon nanotube films as novel and promising ultrafast photocathode material.
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Affiliation(s)
- Mark E Green
- Department of Physics and Optical Science , UNC Charlotte , Charlotte , North Carolina 28223 , United States
| | - Derek A Bas
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Hsin-Yu Yao
- Department of Physics , National Tsing Hua University , No. 101, Section 2, Kuang-Fu Road , Hsinchu , Taiwan
| | - Jamie J Gengler
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | | | - Tyson C Back
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | - Augustine M Urbas
- Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , United States
| | | | | | - Tsing-Hua Her
- Department of Physics and Optical Science , UNC Charlotte , Charlotte , North Carolina 28223 , United States
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37
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Vaida ME, Marsh BM, Leone SR. Nonmetal to Metal Transition and Ultrafast Charge Carrier Dynamics of Zn Clusters on p-Si(100) by fs-XUV Photoemission Spectroscopy. Nano Lett 2018; 18:4107-4114. [PMID: 29856224 DOI: 10.1021/acs.nanolett.8b00700] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding the electronic structure and charge carrier dynamics of supported clusters is important due to their many potential applications in photochemistry and catalysis. In this investigation, photoemission spectroscopy, in conjunction with femtosecond extreme ultraviolet (XUV) laser pulses, is used to investigate the electronic structure and ultrafast charge carrier dynamics at a Si(100) surface decorated with Zn clusters. Static photoemission spectroscopy is used to investigate the changes in the electronic structure as the dimensionality of the Zn is increased from small clusters composed of a very few atoms to metallic Zn particles. Furthermore, femtosecond optical-pump XUV-probe photoemission spectroscopy is employed to induce a charge transfer from the p-Si(100) substrate to the Zn clusters and to measure in real time the charge trapping at the Zn cluster as well as the subsequent charge relaxation. The ultrafast charge carrier dynamics are also investigated for small clusters and metallic Zn particles. Significant transient charging of the Zn clusters after excitation of the Si(100) substrate by 800 nm light is observed for Zn coverages greater than 0.12 ML Zn, which coincides with the formation of a Schottky barrier at the interface between the Zn particle and the p-Si(100) substrate. The transient signals show that the charge trapping time at the Zn cluster varies with the cluster size, which is rationalized based on the electronic structure of the cluster as well as the band energy alignment at the Zn cluster-Si(100) junction.
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Affiliation(s)
- Mihai E Vaida
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
- Department of Physics and Energy Conversion and Propulsion Cluster , University of Central Florida , Orlando , Florida 32816 , United States
| | - Brett M Marsh
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
| | - Stephen R Leone
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
- Department of Physics , University of California , Berkeley , California 94720 , United States
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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38
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Yan H, Narasimha KT, Denlinger J, Li FH, Mo SK, Hohman JN, Dahl JEP, Carlson RMK, Tkachenko BA, Fokin AA, Schreiner PR, Hussain Z, Shen ZX, Melosh NA. Monochromatic Photocathodes from Graphene-Stabilized Diamondoids. Nano Lett 2018; 18:1099-1103. [PMID: 29286670 DOI: 10.1021/acs.nanolett.7b04645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The monochromatic photoemission from diamondoid monolayers provides a new strategy to create electron sources with low energy dispersion and enables compact electron guns with high brightness and low beam emittance for aberration-free imaging, lithography, and accelerators. However, these potential applications are hindered by degradation of diamondoid monolayers under photon irradiation and electron bombardment. Here, we report a graphene-protected diamondoid monolayer photocathode with 4-fold enhancement of stability compared to the bare diamondoid counterpart. The single-layer graphene overcoating preserves the monochromaticity of the photoelectrons, showing 12.5 meV ful width at half-maximum distribution of kinetic energy. Importantly, the graphene coating effectively suppresses desorption of the diamondoid monolayer, enhancing its thermal stability by at least 100 K. Furthermore, by comparing the decay rate at different photon energies, we identify electron bombardment as the principle decay pathway for diamondoids under graphene protection. This provides a generic approach for stabilizing volatile species on photocathode surfaces, which could greatly improve performance of electron emitters.
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Affiliation(s)
- Hao Yan
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
| | - Karthik T Narasimha
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
| | - Jonathan Denlinger
- Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Fei Hua Li
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
| | - Sung-Kwan Mo
- Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - J Nathan Hohman
- Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Jeremy E P Dahl
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
| | - Robert M K Carlson
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
| | | | - Andrey A Fokin
- Institute of Organic Chemistry, Justus-Liebig University , Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus-Liebig University , Giessen, Germany
| | - Zahid Hussain
- Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
- Department of Applied Physics, Stanford University , Stanford, California 94305, United States
| | - Nicholas A Melosh
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences , Stanford, California 94305, United States
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39
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Podbiel D, Kahl P, Makris A, Frank B, Sindermann S, Davis TJ, Giessen H, Hoegen MHV, Meyer Zu Heringdorf FJ. Imaging the Nonlinear Plasmoemission Dynamics of Electrons from Strong Plasmonic Fields. Nano Lett 2017; 17:6569-6574. [PMID: 28945435 DOI: 10.1021/acs.nanolett.7b02235] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We use subcycle time-resolved photoemission microscopy to unambiguously distinguish optically triggered electron emission (photoemission) from effects caused purely by the plasmonic field (termed "plasmoemission"). We find from time-resolved imaging that nonlinear plasmoemission is dominated by the transverse plasmon field component by utilizing a transient standing wave from two counter-propagating plasmon pulses of opposite transverse spin. From plasmonic foci on flat metal surfaces, we observe highly nonlinear plasmoemission up to the fifth power of intensity and quantized energy transfer, which reflects the quantum-mechanical nature of surface plasmons. Our work constitutes the basis for novel plasmonic devices such as nanometer-confined ultrafast electron sources as well as applications in time-resolved electron microscopy.
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Affiliation(s)
- Daniel Podbiel
- Faculty of Physics and CENIDE, University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - Philip Kahl
- Faculty of Physics and CENIDE, University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - Andreas Makris
- Faculty of Physics and CENIDE, University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - Bettina Frank
- Fourth Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Simon Sindermann
- Faculty of Physics and CENIDE, University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - Timothy J Davis
- Fourth Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70550 Stuttgart, Germany
- School of Physics, University of Melbourne , Parkville, Victoria 3052, Australia
| | - Harald Giessen
- Fourth Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Michael Horn-von Hoegen
- Faculty of Physics and CENIDE, University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
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40
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Martinez B, Livache C, Notemgnou Mouafo LD, Goubet N, Keuleyan S, Cruguel H, Ithurria S, Aubin H, Ouerghi A, Doudin B, Lacaze E, Dubertret B, Silly MG, Lobo RPSM, Dayen JF, Lhuillier E. HgSe Self-Doped Nanocrystals as a Platform to Investigate the Effects of Vanishing Confinement. ACS Appl Mater Interfaces 2017; 9:36173-36180. [PMID: 28956432 DOI: 10.1021/acsami.7b10665] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Self-doped colloidal quantum dots (CQDs) attract a strong interest for the design of a new generation of low-cost infrared (IR) optoelectronic devices because of their tunable intraband absorption feature in the mid-IR region. However, very little remains known about their electronic structure which combines confinement and an inverted band structure, complicating the design of optimized devices. We use a combination of IR spectroscopy and photoemission to determine the absolute energy levels of HgSe CQDs with various sizes and surface chemistries. We demonstrate that the filling of the CQD states ranges from 2 electrons per CQD at small sizes (<5 nm) to more than 18 electrons per CQD at large sizes (≈20 nm). HgSe CQDs are also an interesting platform to observe vanishing confinement in colloidal nanoparticles. We present lines of evidence for a semiconductor-to-metal transition at the CQD level, through temperature-dependent absorption and transport measurements. In contrast with bulk systems, the transition is the result of the vanishing confinement rather than the increase of the doping level.
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Affiliation(s)
- Bertille Martinez
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
| | - Clément Livache
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
| | | | - Nicolas Goubet
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
| | - Sean Keuleyan
- Voxtel, Inc., University of Oregon, CAMCOR, 1241 University of Oregon , Eugene, Oregon 97403, United States
| | - Hervé Cruguel
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
| | - Sandrine Ithurria
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Hervé Aubin
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Abdelkarim Ouerghi
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N-Marcoussis , 91460 Marcoussis, France
| | - Bernard Doudin
- Université de Strasbourg, IPCMS-CNRS UMR 7504 , 23 Rue du Loess, 67034 Strasbourg, France
| | - Emmanuelle Lacaze
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
| | - Benoit Dubertret
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Mathieu G Silly
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Ricardo P S M Lobo
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Jean-François Dayen
- Université de Strasbourg, IPCMS-CNRS UMR 7504 , 23 Rue du Loess, 67034 Strasbourg, France
| | - Emmanuel Lhuillier
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
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41
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Hobbs RG, Putnam WP, Fallahi A, Yang Y, Kärtner FX, Berggren KK. Mapping Photoemission and Hot-Electron Emission from Plasmonic Nanoantennas. Nano Lett 2017; 17:6069-6076. [PMID: 28926275 DOI: 10.1021/acs.nanolett.7b02495] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Understanding plasmon-mediated electron emission and energy transfer on the nanometer length scale is critical to controlling light-matter interactions at nanoscale dimensions. In a high-resolution lithographic material, electron emission and energy transfer lead to chemical transformations. In this work, we employ such chemical transformations in two different high-resolution electron-beam lithography resists, poly(methyl methacrylate) (PMMA) and hydrogen silsesquioxane (HSQ), to map local electron emission and energy transfer with nanometer resolution from plasmonic nanoantennas excited by femtosecond laser pulses. We observe exposure of the electron-beam resists (both PMMA and HSQ) in regions on the surface of nanoantennas where the local field is significantly enhanced. Exposure in these regions is consistent with previously reported optical-field-controlled electron emission from plasmonic hotspots as well as earlier work on low-electron-energy scanning probe lithography. For HSQ, in addition to exposure in hotspots, we observe resist exposure at the centers of rod-shaped nanoantennas in addition to exposure in plasmonic hotspots. Optical field enhancement is minimized at the center of nanorods suggesting that exposure in these regions involves a different mechanism to that in plasmonic hotspots. Our simulations suggest that exposure at the center of nanorods results from the emission of hot electrons produced via plasmon decay in the nanorods. Overall, the results presented in this work provide a means to map both optical-field-controlled electron emission and hot-electron transfer from nanoparticles via chemical transformations produced locally in lithographic materials.
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Affiliation(s)
- Richard G Hobbs
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - William P Putnam
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
- Department of Physics and Center for Ultrafast Imaging, University of Hamburg , Hamburg, Germany
- Northrop Grumman Corporation, NG Next , Redondo Beach, California 90254, United States
| | - Arya Fallahi
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron , 22607 Hamburg, Germany
| | - Yujia Yang
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Franz X Kärtner
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
- Department of Physics and Center for Ultrafast Imaging, University of Hamburg , Hamburg, Germany
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron , 22607 Hamburg, Germany
| | - Karl K Berggren
- Research Laboratory of Electronics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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42
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Ponzoni S, Achilli S, Pintossi C, Drera G, Sangaletti L, Castrucci P, De Crescenzi M, Pagliara S. Hybridized C-O-Si Interface States at the Origin of Efficiency Improvement in CNT/Si Solar Cells. ACS Appl Mater Interfaces 2017; 9:16627-16634. [PMID: 28425281 DOI: 10.1021/acsami.7b01766] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Despite the astonishing values of the power conversion efficiency reached, in just less than a decade, by the carbon nanotube/silicon (CNT/Si) solar cells, many doubts remain on the underlying transport mechanisms across the CNT/Si heterojunction. Here, by combining transient optical spectroscopy in the femtosecond timescale, X-ray photoemission, and a systematic tracking of I-V curves across all phases of the interlayer SiOx growth at the interface, we grasp the mechanism that adequately preserves charge separation at the junction, hindering the photoexcited carrier recombination. Moreover, supported by ab initio calculations aimed to model the complex CNT-Si heterointerface, we show that oxygen-related states at the interface act as entrapping centers for the photoexcited electrons, thus preventing recombination with holes that can flow from Si to CNT across the SiOx layer.
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Affiliation(s)
- Stefano Ponzoni
- I-LAMP and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore , 25121 Brescia, Italy
| | - Simona Achilli
- I-LAMP and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore , 25121 Brescia, Italy
- CNR - National Research Council of Italy, ISTM , via Golgi 19, 20133 Milano, Italy
| | - Chiara Pintossi
- I-LAMP and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore , 25121 Brescia, Italy
| | - Giovanni Drera
- I-LAMP and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore , 25121 Brescia, Italy
| | - Luigi Sangaletti
- I-LAMP and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore , 25121 Brescia, Italy
| | - Paola Castrucci
- Dipartimento di Fisica, Università degli Studi di Roma Tor Vergata , via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - Maurizio De Crescenzi
- Dipartimento di Fisica, Università degli Studi di Roma Tor Vergata , via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - Stefania Pagliara
- I-LAMP and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore , 25121 Brescia, Italy
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43
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Makarov NS, Lim J, Lin Q, Lewellen JW, Moody NA, Robel I, Pietryga JM. Quantum Dot Thin-Films as Rugged, High-Performance Photocathodes. Nano Lett 2017; 17:2319-2327. [PMID: 28253617 DOI: 10.1021/acs.nanolett.6b05175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Typical use of colloidal quantum dots (QDs) as bright, tunable phosphors in real applications relies on engineering of their surfaces to suppress the loss of excited carriers to surface trap states or to the surrounding medium. Here, we explore the utility of QDs in an application that actually exploits their propensity toward photoionization, namely within efficient and robust photocathodes for use in next-generation electron guns. In order to establish the relevance of QD films as photocathodes, we evaluate the efficiency of electron photoemission of films of a variety of compositions in a typical electron gun configuration. By quantifying photocurrent as a function of excitation photon energy, excitation intensity and pulse duration, we establish the role of hot electrons in photoemission within the multiphoton excitation regime. We also demonstrate the effect of QD structure and film deposition methods on efficiency, which suggests numerous pathways for further enhancements. Finally, we show that QD photocathodes offer superior efficiencies relative to standard copper cathodes and are robust against degradation under ambient conditions.
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Affiliation(s)
- Nikolay S Makarov
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Jaehoon Lim
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Qianglu Lin
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - John W Lewellen
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Nathan A Moody
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - István Robel
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Jeffrey M Pietryga
- Chemistry Division and ‡Accelerator Operations and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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44
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Mo SK. Angle-resolved photoemission spectroscopy for the study of two-dimensional materials. Nano Converg 2017; 4:6. [PMCID: PMC6141890 DOI: 10.1186/s40580-017-0100-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/15/2017] [Indexed: 05/26/2023]
Abstract
Quantum systems in confined geometries allow novel physical properties that cannot easily be attained in their bulk form. These properties are governed by the changes in the band structure and the lattice symmetry, and most pronounced in their single layer limit. Angle-resolved photoemission spectroscopy (ARPES) is a direct tool to investigate the underlying changes of band structure to provide essential information for understanding and controlling such properties. In this review, recent progresses in ARPES as a tool to study two-dimensional atomic crystals have been presented. ARPES results from few-layer and bulk crystals of material class often referred as “beyond graphene” are discussed along with the relevant developments in the instrumentation.
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Affiliation(s)
- Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
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Feng Y, Liu D, Feng B, Liu X, Zhao L, Xie Z, Liu Y, Liang A, Hu C, Hu Y, He S, Liu G, Zhang J, Chen C, Xu Z, Chen L, Wu K, Liu YT, Lin H, Huang ZQ, Hsu CH, Chuang FC, Bansil A, Zhou XJ. Direct evidence of interaction-induced Dirac cones in a monolayer silicene/Ag(111) system. Proc Natl Acad Sci U S A 2016; 113:14656-61. [PMID: 27930314 DOI: 10.1073/pnas.1613434114] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Silicene, analogous to graphene, is a one-atom-thick 2D crystal of silicon, which is expected to share many of the remarkable properties of graphene. The buckled honeycomb structure of silicene, along with enhanced spin-orbit coupling, endows silicene with considerable advantages over graphene in that the spin-split states in silicene are tunable with external fields. Although the low-energy Dirac cone states lie at the heart of all novel quantum phenomena in a pristine sheet of silicene, a hotly debated question is whether these key states can survive when silicene is grown or supported on a substrate. Here we report our direct observation of Dirac cones in monolayer silicene grown on a Ag(111) substrate. By performing angle-resolved photoemission measurements on silicene(3 × 3)/Ag(111), we reveal the presence of six pairs of Dirac cones located on the edges of the first Brillouin zone of Ag(111), which is in sharp contrast to the expected six Dirac cones centered at the K points of the primary silicene(1 × 1) Brillouin zone. Our analysis shows clearly that the unusual Dirac cone structure we have observed is not tied to pristine silicene alone but originates from the combined effects of silicene(3 × 3) and the Ag(111) substrate. Our study thus identifies the case of a unique type of Dirac cone generated through the interaction of two different constituents. The observation of Dirac cones in silicene/Ag(111) opens a unique materials platform for investigating unusual quantum phenomena and for applications based on 2D silicon systems.
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Abstract
The benefits of the hot electrons from semiconductor nanostructures in photocatalysis or photovoltaics result from their higher energy compared to that of the band-edge electrons facilitating the electron-transfer process. The production of high-energy hot electrons usually requires short-wavelength UV or intense multiphoton visible excitation. Here, we show that highly energetic hot electrons capable of above-threshold ionization are produced via exciton-to-hot-carrier up-conversion in Mn-doped quantum dots under weak band gap excitation (∼10 W/cm2) achievable with the concentrated solar radiation. The energy of hot electrons is as high as ∼0.4 eV above the vacuum level, much greater than those observed in other semiconductor or plasmonic metal nanostructures, which are capable of performing energetically and kinetically more-challenging electron transfer. Furthermore, the prospect of generating solvated electron is unique for the energetic hot electrons from up-conversion, which can open a new door for long-range electron transfer beyond short-range interfacial electron transfer.
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Affiliation(s)
- Yitong Dong
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
| | - David Parobek
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
| | - Daniel Rossi
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
| | - Dong Hee Son
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
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Abstract
Layered semiconductor compounds represent alternative electronic materials beyond graphene. WSe2 is one of the two-dimensional materials with wide potential in opto- and nanoelectronics and is often used to construct novel three-dimensional architectures with new functionalities. Here, we report the topography and the electronic property of the WSe2 characterized by means of scanning tunneling microscopy and spectroscopy (STM and STS), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry. The STM images reveal the presence of atomic-size imperfections and a variation in the electronic structure caused by the presence of defects and impurities below the detection limit of XPS. Both STS and photoemission reveal a spatial variation in the Fermi level position. The analysis of the core levels indicates the presence of different doping levels. The presence of a large concentration of defects and impurities has a strong impact on the electronic properties of the WSe2 surface. Our findings demonstrate that the growth of controllable and high quality two-dimensional materials at nanometer scale is one of the most challenging tasks that requires further attention.
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Affiliation(s)
- Rafik Addou
- Department of Materials Science, Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Robert M Wallace
- Department of Materials Science, Engineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
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48
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Abstract
In order to understand the physical and chemical properties of advanced materials, functional molecular adsorbates, and protein structures, a detailed knowledge of the atomic arrangement is essential. Up to now, if subsurface structures are under investigation, only indirect methods revealed reliable results of the atoms' spatial arrangement. An alternative and direct method is three-dimensional imaging by means of holography. Holography was in fact proposed for electron waves, because of the electrons' short wavelength at easily accessible energies. Further, electron waves are ideal structure probes on an atomic length scale, because electrons have a high scattering probability even for light elements. However, holographic reconstructions of electron diffraction patterns have in the past contained severe image artifacts and were limited to at most a few tens of atoms. Here, we present a general reconstruction algorithm that leads to high-quality atomic images showing thousands of atoms. Additionally, we show that different elements can be identified by electron holography for the example of FeS2.
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Affiliation(s)
- Tobias Lühr
- Experimental Physics I, TU Dortmund , 44221 Dortmund, Germany
| | - Aimo Winkelmann
- Experimental Department I, Max Planck Institute of Microstructure Physics , 06120 Halle, Germany
| | - Gert Nolze
- Department 5 - Materials Engineering, BAM - Federal Institute for Materials Research and Testing , 12205 Berlin, Germany
| | - Dominique Krull
- Experimental Physics I, TU Dortmund , 44221 Dortmund, Germany
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Miccio LA, Setvin M, Müller M, Abadía M, Piquero I, Lobo-Checa J, Schiller F, Rogero C, Schmid M, Sánchez-Portal D, Diebold U, Ortega JE. Interplay between Steps and Oxygen Vacancies on Curved TiO2(110). Nano Lett 2016; 16:2017-22. [PMID: 26752001 DOI: 10.1021/acs.nanolett.5b05286] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A vicinal rutile TiO2(110) crystal with a smooth variation of atomic steps parallel to the [1-10] direction was analyzed locally with STM and ARPES. The step edge morphology changes across the samples, from [1-11] zigzag faceting to straight [1-10] steps. A step-bunching phase is attributed to an optimal (110) terrace width, where all bridge-bonded O atom vacancies (Obr vacs) vanish. The [1-10] steps terminate with a pair of 2-fold coordinated O atoms, which give rise to bright, triangular protrusions (St) in STM. The intensity of the Ti 3d-derived gap state correlates with the sum of Obr vacs plus St protrusions at steps, suggesting that both Obr vacs and steps contribute a similar effective charge to sample doping. The binding energy of the gap state shifts when going from the flat (110) surface toward densely stepped planes, pointing to differences in the Ti(3+) polaron near steps and at terraces.
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Affiliation(s)
- Luis A Miccio
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC) , 20018 San Sebastián, Spain
| | - Martin Setvin
- Institute of Applied Physics, Vienna University of Technology , Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria
| | - Moritz Müller
- CIC nanoGUNE , Avenido Tolosa 76, 20018 San Sebastián, Spain
| | - Mikel Abadía
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
| | - Ignacio Piquero
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
| | - Jorge Lobo-Checa
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
| | - Frederik Schiller
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität Marburg , 35032 Marburg, Germany
| | - Celia Rogero
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
| | - Michael Schmid
- Institute of Applied Physics, Vienna University of Technology , Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria
| | - Daniel Sánchez-Portal
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC) , 20018 San Sebastián, Spain
| | - Ulrike Diebold
- Institute of Applied Physics, Vienna University of Technology , Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria
| | - J Enrique Ortega
- Centro de Física de Materiales (CSIC-UPV/EHU) , Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC) , 20018 San Sebastián, Spain
- Departamento de Física Aplicada, Universidad del País Vasco (UPV/EHU) , 20080 San Sebastián, Spain
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Yeh PC, Jin W, Zaki N, Kunstmann J, Chenet D, Arefe G, Sadowski JT, Dadap JI, Sutter P, Hone J, Osgood RM. Direct Measurement of the Tunable Electronic Structure of Bilayer MoS2 by Interlayer Twist. Nano Lett 2016; 16:953-959. [PMID: 26760447 DOI: 10.1021/acs.nanolett.5b03883] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using angle-resolved photoemission on micrometer-scale sample areas, we directly measure the interlayer twist angle-dependent electronic band structure of bilayer molybdenum-disulfide (MoS2). Our measurements, performed on arbitrarily stacked bilayer MoS2 flakes prepared by chemical vapor deposition, provide direct evidence for a downshift of the quasiparticle energy of the valence band at the Brillouin zone center (Γ̅ point) with the interlayer twist angle, up to a maximum of 120 meV at a twist angle of ∼40°. Our direct measurements of the valence band structure enable the extraction of the hole effective mass as a function of the interlayer twist angle. While our results at Γ̅ agree with recently published photoluminescence data, our measurements of the quasiparticle spectrum over the full 2D Brillouin zone reveal a richer and more complicated change in the electronic structure than previously theoretically predicted. The electronic structure measurements reported here, including the evolution of the effective mass with twist-angle, provide new insight into the physics of twisted transition-metal dichalcogenide bilayers and serve as a guide for the practical design of MoS2 optoelectronic and spin-/valley-tronic devices.
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Affiliation(s)
- Po-Chun Yeh
- Department of Electrical Engineering, Columbia University , New York, New York 10027, United States
| | - Wencan Jin
- Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States
| | - Nader Zaki
- Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States
| | - Jens Kunstmann
- Department of Chemistry, Columbia University , New York, New York 10027, United States
- Theoretical Chemistry, TU Dresden , 01062 Dresden, Germany
| | - Daniel Chenet
- Department of Mechanical Engineering, Columbia University , New York, New York 10027, United States
| | - Ghidewon Arefe
- Department of Mechanical Engineering, Columbia University , New York, New York 10027, United States
| | - Jerzy T Sadowski
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Jerry I Dadap
- Department of Electrical Engineering, Columbia University , New York, New York 10027, United States
| | - Peter Sutter
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States
| | - James Hone
- Department of Mechanical Engineering, Columbia University , New York, New York 10027, United States
| | - Richard M Osgood
- Department of Electrical Engineering, Columbia University , New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States
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