1
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Thomas JC, Chen W, Xiong Y, Barker BA, Zhou J, Chen W, Rossi A, Kelly N, Yu Z, Zhou D, Kumari S, Barnard ES, Robinson JA, Terrones M, Schwartzberg A, Ogletree DF, Rotenberg E, Noack MM, Griffin S, Raja A, Strubbe DA, Rignanese GM, Weber-Bargioni A, Hautier G. A substitutional quantum defect in WS 2 discovered by high-throughput computational screening and fabricated by site-selective STM manipulation. Nat Commun 2024; 15:3556. [PMID: 38670956 DOI: 10.1038/s41467-024-47876-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
Point defects in two-dimensional materials are of key interest for quantum information science. However, the parameter space of possible defects is immense, making the identification of high-performance quantum defects very challenging. Here, we perform high-throughput (HT) first-principles computational screening to search for promising quantum defects within WS2, which present localized levels in the band gap that can lead to bright optical transitions in the visible or telecom regime. Our computed database spans more than 700 charged defects formed through substitution on the tungsten or sulfur site. We found that sulfur substitutions enable the most promising quantum defects. We computationally identify the neutral cobalt substitution to sulfur (CoS 0 ) and fabricate it with scanning tunneling microscopy (STM). The CoS 0 electronic structure measured by STM agrees with first principles and showcases an attractive quantum defect. Our work shows how HT computational screening and nanoscale synthesis routes can be combined to design promising quantum defects.
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Affiliation(s)
- John C Thomas
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA.
| | - Wei Chen
- Institute of Condensed Matter and Nanoscicence, Université Catholique de Louvain, Louvain-la-Neuve, 1348, Belgium
| | - Yihuang Xiong
- Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA
| | - Bradford A Barker
- Department of Physics, University of California, Merced, Merced, CA, 95343, USA
| | - Junze Zhou
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Weiru Chen
- Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA
| | - Antonio Rossi
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Nolan Kelly
- Department of Physics, University of California, Merced, Merced, CA, 95343, USA
| | - Zhuohang Yu
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA
- Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Da Zhou
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Shalini Kumari
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA
- Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Edward S Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA
- Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mauricio Terrones
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA
- Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Adam Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Eli Rotenberg
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Marcus M Noack
- Applied Mathematics and Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sinéad Griffin
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Archana Raja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - David A Strubbe
- Department of Physics, University of California, Merced, Merced, CA, 95343, USA
| | - Gian-Marco Rignanese
- Institute of Condensed Matter and Nanoscicence, Université Catholique de Louvain, Louvain-la-Neuve, 1348, Belgium
| | - Alexander Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Geoffroy Hautier
- Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA.
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2
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Rossi A, Johnson C, Balgley J, Thomas JC, Francaviglia L, Dettori R, Schmid AK, Watanabe K, Taniguchi T, Cothrine M, Mandrus DG, Jozwiak C, Bostwick A, Henriksen EA, Weber-Bargioni A, Rotenberg E. Direct Visualization of the Charge Transfer in a Graphene/α-RuCl 3 Heterostructure via Angle-Resolved Photoemission Spectroscopy. Nano Lett 2023; 23:8000-8005. [PMID: 37639696 PMCID: PMC10510581 DOI: 10.1021/acs.nanolett.3c01974] [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: 05/26/2023] [Revised: 08/21/2023] [Indexed: 08/31/2023]
Abstract
We investigate the electronic properties of a graphene and α-ruthenium trichloride (α-RuCl3) heterostructure using a combination of experimental techniques. α-RuCl3 is a Mott insulator and a Kitaev material. Its combination with graphene has gained increasing attention due to its potential applicability in novel optoelectronic devices. By using a combination of spatially resolved photoemission spectroscopy and low-energy electron microscopy, we are able to provide a direct visualization of the massive charge transfer from graphene to α-RuCl3, which can modify the electronic properties of both materials, leading to novel electronic phenomena at their interface. A measurement of the spatially resolved work function allows for a direct estimate of the interface dipole between graphene and α-RuCl3. Their strong coupling could lead to new ways of manipulating electronic properties of a two-dimensional heterojunction. Understanding the electronic properties of this structure is pivotal for designing next generation low-power optoelectronics devices.
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Affiliation(s)
- Antonio Rossi
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Center
for Nanotechnology Innovation @ NEST, Istituto
Italiano di Tecnologia, Pisa 56127, Italy
| | - Cameron Johnson
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Jesse Balgley
- Department
of Physics and Institute for Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - John C. Thomas
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Luca Francaviglia
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Riccardo Dettori
- Physical
and Life Sciences Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Andreas K. Schmid
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Matthew Cothrine
- Material
Science & Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - David G. Mandrus
- Material
Science & Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Chris Jozwiak
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Erik A. Henriksen
- Department
of Physics and Institute for Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Alexander Weber-Bargioni
- The
Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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3
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Zhou J, Barnard E, Cabrini S, Munechika K, Schwartzberg A, Weber-Bargioni A. Integrating collapsible plasmonic gaps on near-field probes for polarization-resolved mapping of plasmon-enhanced emission in 2D material. Opt Express 2023; 31:20440-20448. [PMID: 37381438 DOI: 10.1364/oe.490112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 05/16/2023] [Indexed: 06/30/2023]
Abstract
Scanning near-field optical microscopy (SNOM) is an important technique used to study the optical properties of material systems at the nanoscale. In previous work, we reported on the use of nanoimprinting to improve the reproducibility and throughput of near-field probes including complicated optical antenna structures such as the 'campanile' probe. However, precise control over the plasmonic gap size, which determines the near-field enhancement and spatial resolution, remains a challenge. Here, we present a novel approach to fabricating a sub-20 nm plasmonic gap in a near-field plasmonic probe through the controlled collapse of imprinted nanostructures using atomic layer deposition (ALD) coatings to define the gap width. The resulting ultranarrow gap at the apex of the probe provides a strong polarization-sensitive near-field optical response, which results in an enhancement of the optical transmission in a broad wavelength range from 620 to 820 nm, enabling tip-enhanced photoluminescence (TEPL) mapping of 2-dimensional (2D) materials. We demonstrate the potential of this near-field probe by mapping a 2D exciton coupled to a linearly polarized plasmonic resonance with below 30 nm spatial resolution. This work proposes a novel approach for integrating a plasmonic antenna at the apex of the near-field probe, paving the way for the fundamental study of light-matter interactions at the nanoscale.
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4
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Zhou J, Thomas JC, Barre E, Barnard ES, Raja A, Cabrini S, Munechika K, Schwartzberg A, Weber-Bargioni A. Near-Field Coupling with a Nanoimprinted Probe for Dark Exciton Nanoimaging in Monolayer WSe 2. Nano Lett 2023. [PMID: 37262350 DOI: 10.1021/acs.nanolett.3c00621] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Tip-enhanced photoluminescence (TRPL) is a powerful technique for spatially and spectrally probing local optical properties of 2-dimensional (2D) materials that are modulated by the local heterogeneities, revealing inaccessible dark states due to bright state overlap in conventional far-field microscopy at room temperature. While scattering-type near-field probes have shown the potential to selectively enhance and reveal dark exciton emission, their technical complexity and sensitivity can pose challenges under certain experimental conditions. Here, we present a highly reproducible and easy-to-fabricate near-field probe based on nanoimprint lithography and fiber-optic excitation and collection. The novel near-field measurement configuration provides an ∼3 orders of magnitude out-of-plane Purcell enhancement, diffraction-limited excitation spot, and subdiffraction hyperspectral imaging resolution (below 50 nm) of dark exciton emission. The effectiveness of this high spatial XD mapping technique was then demonstrated through reproducible hyperspectral mapping of oxidized sites and bubble areas.
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Affiliation(s)
- Junze Zhou
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - John C Thomas
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Elyse Barre
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Edward S Barnard
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Archana Raja
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Stefano Cabrini
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Keiko Munechika
- HighRI Optics, Inc. 5401 Broadway Ter 304, Oakland, California 94618, United States
| | - Adam Schwartzberg
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Alexander Weber-Bargioni
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
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5
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Zhou J, Gashi A, Riminucci F, Chang B, Barnard E, Cabrini S, Weber-Bargioni A, Schwartzberg A, Munechika K. Sharp, high numerical aperture (NA), nanoimprinted bare pyramid probe for optical mapping. Rev Sci Instrum 2023; 94:033902. [PMID: 37012819 DOI: 10.1063/5.0104012] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 02/02/2023] [Indexed: 06/19/2023]
Abstract
The ability to correlate optical hyperspectral mapping and high resolution topographic imaging is critically important to gain deep insight into the structure-function relationship of nanomaterial systems. Scanning near-field optical microscopy can achieve this goal, but at the cost of significant effort in probe fabrication and experimental expertise. To overcome these two limitations, we have developed a low-cost and high-throughput nanoimprinting technique to integrate a sharp pyramid structure on the end facet of a single-mode fiber that can be scanned with a simple tuning-fork technique. The nanoimprinted pyramid has two main features: (1) a large taper angle (∼70°), which determines the far-field confinement at the tip, resulting in a spatial resolution of 275 nm, an effective numerical aperture of 1.06, and (2) a sharp apex with a radius of curvature of ∼20 nm, which enables high resolution topographic imaging. Optical performance is demonstrated through evanescent field distribution mapping of a plasmonic nanogroove sample, followed by hyperspectral photoluminescence mapping of nanocrystals using a fiber-in-fiber-out light coupling mode. Through comparative photoluminescence mapping on 2D monolayers, we also show a threefold improvement in spatial resolution over chemically etched fibers. These results show that the bare nanoimprinted near-field probes provide simple access to spectromicroscopy correlated with high resolution topographic mapping and have the potential to advance reproducible fiber-tip-based scanning near-field microscopy.
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Affiliation(s)
- Junze Zhou
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Arian Gashi
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Fabrizio Riminucci
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Boyce Chang
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Edward Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Stefano Cabrini
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Alexander Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Adam Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Keiko Munechika
- HighRI Optics, Inc., 5401 Broadway Ter 304, Oakland, California 94618, USA
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6
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Zhu T, Ruan W, Wang YQ, Tsai HZ, Wang S, Zhang C, Wang T, Liou F, Watanabe K, Taniguchi T, Neaton JB, Weber-Bargioni A, Zettl A, Qiu ZQ, Zhang G, Wang F, Moore JE, Crommie MF. Imaging gate-tunable Tomonaga-Luttinger liquids in 1H-MoSe 2 mirror twin boundaries. Nat Mater 2022; 21:748-753. [PMID: 35710632 DOI: 10.1038/s41563-022-01277-3] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 04/25/2022] [Indexed: 06/15/2023]
Abstract
One-dimensional electron systems exhibit fundamentally different properties than higher-dimensional systems. For example, electron-electron interactions in one-dimensional electron systems have been predicted to induce Tomonaga-Luttinger liquid behaviour. Naturally occurring grain boundaries in single-layer transition metal dichalcogenides exhibit one-dimensional conducting channels that have been proposed to host Tomonaga-Luttinger liquids, but charge density wave physics has also been suggested to explain their behaviour. Clear identification of the electronic ground state of this system has been hampered by an inability to electrostatically gate such boundaries and tune their charge carrier concentration. Here we present a scanning tunnelling microscopy and spectroscopy study of gate-tunable mirror twin boundaries in single-layer 1H-MoSe2 devices. Gating enables scanning tunnelling microscopy and spectroscopy for different mirror twin boundary electron densities, thus allowing precise characterization of electron-electron interaction effects. Visualization of the resulting mirror twin boundary electronic structure allows unambiguous identification of collective density wave excitations having two velocities, in quantitative agreement with the spin-charge separation predicted by finite-length Tomonaga-Luttinger liquid theory.
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Affiliation(s)
- Tiancong Zhu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Wei Ruan
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Physics, University of California, Berkeley, CA, USA.
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China.
| | - Yan-Qi Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Hsin-Zon Tsai
- Department of Physics, University of California, Berkeley, CA, USA
| | - Shuopei Wang
- Beijing National Laboratory for Condensed Matter Physics, Key Laboratory for Nanoscale Physics and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Songshan Lake Materials Laboratory, Dongguan, China
| | - Canxun Zhang
- Department of Physics, University of California, Berkeley, CA, USA
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Tianye Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Franklin Liou
- Department of Physics, University of California, Berkeley, CA, USA
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Jeffrey B Neaton
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Alexander Weber-Bargioni
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Alex Zettl
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Z Q Qiu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Guangyu Zhang
- Beijing National Laboratory for Condensed Matter Physics, Key Laboratory for Nanoscale Physics and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Songshan Lake Materials Laboratory, Dongguan, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Feng Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Physics, University of California, Berkeley, CA, USA.
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Joel E Moore
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Physics, University of California, Berkeley, CA, USA.
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Michael F Crommie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Physics, University of California, Berkeley, CA, USA.
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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7
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Francaviglia L, Zipfel J, Carlstroem J, Sridhar S, Riminucci F, Blach D, Wong E, Barnard E, Watanabe K, Taniguchi T, Weber-Bargioni A, Ogletree DF, Aloni S, Raja A. Optimizing cathodoluminescence microscopy of buried interfaces through nanoscale heterostructure design. Nanoscale 2022; 14:7569-7578. [PMID: 35502865 DOI: 10.1039/d1nr08082b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mapping the optical response of buried interfaces with nanoscale spatial resolution is crucial in several systems where an active component is embedded within a buffer layer for structural or functional reasons. Here, we demonstrate that cathodoluminescence microscopy is not only an ideal tool for visualizing buried interfaces, but can be optimized through heterostructure design. We focus on the prototypical system of monolayers of semiconducting transition metal dichalcogenide sandwiched between hexagonal boron nitride layers. We leverage the encapsulating layers to tune the nanoscale spatial resolution achievable in cathodoluminescence mapping while also controlling the brightness of the emission. Thicker encapsulation layers result in a brighter emission while thinner ones enhance the spatial resolution at the expense of the signal intensity. We find that a favorable trade-off between brightness and resolution is achievable up to about ∼100 nm of total encapsulation. Beyond this value, the brightness gain is marginal, while the spatial resolution enters a regime that is achievable by diffraction-limited optical microscopy. By preparing samples of varying encapsulation thickness, we are able to determine a surprisingly isotropic exciton diffusion length of >200 nm within the hexagonal boron nitride which is the dominant factor that determines spatial resolution. We further demonstrate that we can overcome the exciton diffusion-limited spatial resolution by using spectrally distinct signals, which is the case for nanoscale inhomogeneities within monolayer transition metal dichalcogenides.
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Affiliation(s)
- Luca Francaviglia
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Jonas Zipfel
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Johan Carlstroem
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Sriram Sridhar
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Fabrizio Riminucci
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
- Dipartimento di Fisica, Università del Salento, Strada Provinciale Lecce-Monteroni, Campus Ecotekne, Lecce, 73100, Italy
| | - Daria Blach
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
- Department of Chemistry, Purdue University, West Lafayette, IN 47909, USA
| | - Ed Wong
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Edward Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | | | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
| | - Archana Raja
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, USA.
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8
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Cochrane KA, Lee JH, Kastl C, Haber JB, Zhang T, Kozhakhmetov A, Robinson JA, Terrones M, Repp J, Neaton JB, Weber-Bargioni A, Schuler B. Spin-dependent vibronic response of a carbon radical ion in two-dimensional WS 2. Nat Commun 2021; 12:7287. [PMID: 34911952 PMCID: PMC8674275 DOI: 10.1038/s41467-021-27585-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 11/22/2021] [Indexed: 11/29/2022] Open
Abstract
Atomic spin centers in 2D materials are a highly anticipated building block for quantum technologies. Here, we demonstrate the creation of an effective spin-1/2 system via the atomically controlled generation of magnetic carbon radical ions (CRIs) in synthetic two-dimensional transition metal dichalcogenides. Hydrogenated carbon impurities located at chalcogen sites introduced by chemical doping are activated with atomic precision by hydrogen depassivation using a scanning probe tip. In its anionic state, the carbon impurity is computed to have a magnetic moment of 1 μB resulting from an unpaired electron populating a spin-polarized in-gap orbital. We show that the CRI defect states couple to a small number of local vibrational modes. The vibronic coupling strength critically depends on the spin state and differs for monolayer and bilayer WS2. The carbon radical ion is a surface-bound atomic defect that can be selectively introduced, features a well-understood vibronic spectrum, and is charge state controlled. Spin-polarized defects in 2D materials are attracting attention for future quantum technology applications, but their controlled fabrication is still challenging. Here, the authors report the creation and characterization of effective spin 1/2 defects via the atomically-precise generation of magnetic carbon radical ions in 2D WS2.
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Affiliation(s)
- Katherine A Cochrane
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jun-Ho Lee
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Christoph Kastl
- Walter-Schottky-Institut and Physik-Department, Technical University of Munich, Garching, 85748, Germany
| | - Jonah B Haber
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Tianyi Zhang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA.,Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Azimkhan Kozhakhmetov
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA
| | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA.,Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mauricio Terrones
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA.,Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA.,Department of Physics and Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, 93040, Germany
| | - Jeffrey B Neaton
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. .,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA. .,Kavli Energy Nanosciences Institute at Berkeley, Berkeley, CA, 94720, USA.
| | | | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. .,nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland.
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9
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Luna M, Barawi M, Gómez-Moñivas S, Colchero J, Rodríguez-Peña M, Yang S, Zhao X, Lu YH, Chintala R, Reñones P, Altoe V, Martínez L, Huttel Y, Kawasaki S, Weber-Bargioni A, de la Peña ÓShea VA, Yang P, Ashby PD, Salmeron M. Photoinduced Charge Transfer and Trapping on Single Gold Metal Nanoparticles on TiO 2. ACS Appl Mater Interfaces 2021; 13:50531-50538. [PMID: 34641675 PMCID: PMC8554764 DOI: 10.1021/acsami.1c13662] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 07/19/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
We present a study of the effect of gold nanoparticles (Au NPs) on TiO2 on charge generation and trapping during illumination with photons of energy larger than the substrate band gap. We used a novel characterization technique, photoassisted Kelvin probe force microscopy, to study the process at the single Au NP level. We found that the photoinduced electron transfer from TiO2 to the Au NP increases logarithmically with light intensity due to the combined contribution of electron-hole pair generation in the space charge region in the TiO2-air interface and in the metal-semiconductor junction. Our measurements on single particles provide direct evidence for electron trapping that hinders electron-hole recombination, a key factor in the enhancement of photo(electro)catalytic activity.
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Affiliation(s)
- Monica Luna
- IMN-Instituto
de Micro y Nanotecnología (CNM-CSIC), 28760 Tres Cantos, Spain
| | - Mariam Barawi
- Photoactivated
Processes Unit, IMDEA-ENERGIA, 28935 Móstoles, Spain
| | - Sacha Gómez-Moñivas
- Departamento
de Ingeniería Informática, Escuela Politécnica
Superior, Universidad Autónoma de
Madrid, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Jaime Colchero
- Departamento
de Física, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain
| | | | - Shanshan Yang
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Xiao Zhao
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Yi-Hsien Lu
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Ravi Chintala
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | - Patricia Reñones
- Photoactivated
Processes Unit, IMDEA-ENERGIA, 28935 Móstoles, Spain
| | - Virginia Altoe
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | - Lidia Martínez
- Instituto
de Ciencia de Materiales de Madrid (ICMM-CSIC), 28049 Madrid, Spain
| | - Yves Huttel
- Instituto
de Ciencia de Materiales de Madrid (ICMM-CSIC), 28049 Madrid, Spain
| | - Seiji Kawasaki
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Alexander Weber-Bargioni
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | | | - Peidong Yang
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Paul D. Ashby
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | - Miquel Salmeron
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
- Materials
Science and Engineering Department, University
of California Berkeley, Berkeley, California 94720, United States
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10
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Li S, Francaviglia L, Kohler DD, Jones ZR, Zhao ET, Ogletree DF, Weber-Bargioni A, Melosh NA, Hamers RJ. Ag-Diamond Core-Shell Nanostructures Incorporated with Silicon-Vacancy Centers. ACS Mater Au 2021; 2:85-93. [PMID: 36855764 PMCID: PMC9888652 DOI: 10.1021/acsmaterialsau.1c00027] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Silicon-vacancy (SiV) centers in diamond have attracted attention as highly stable fluorophores for sensing and as possible candidates for quantum information science. While prior studies have shown that the formation of hybrid diamond-metal structures can increase the rates of optical absorption and emission, many practical applications require diamond plasmonic structures that are stable in harsh chemical and thermal environments. Here, we demonstrate that Ag nanospheres, produced both in quasi-random arrays by thermal dewetting and in ordered arrays using electron-beam lithography, can be completely encapsulated with a thin diamond coating containing SiV centers, leading to hybrid core-shell nanostructures exhibiting extraordinary chemical and thermal stability as well as enhanced optical properties. Diamond shells with a thickness on the order of 20-100 nm are sufficient to encapsulate and protect the Ag nanostructures with different sizes ranging from 20 nm to hundreds of nanometers, allowing them to withstand heating to temperatures of 1000 °C and immersion in harsh boiling acid for 24 h. Ultrafast photoluminescence lifetime and super-resolution optical imaging experiments were used to study the SiV properties on and off the core-shell structures, which show that the SiV on core-shell structures have higher brightness and faster decay rate. The stability and optical properties of the hybrid Ag-diamond core-shell structures make them attractive candidates for high-efficiency imaging and quantum-based sensing applications.
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Affiliation(s)
- Shuo Li
- Department
of Chemistry, University of Wisconsin—Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States,Stanford
Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States,Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - Luca Francaviglia
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Daniel D. Kohler
- Department
of Chemistry, University of Wisconsin—Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Zachary R. Jones
- Department
of Chemistry, University of Wisconsin—Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Eric T. Zhao
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - D. Frank Ogletree
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alexander Weber-Bargioni
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Nicholas A. Melosh
- Stanford
Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States,Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States,
| | - Robert J. Hamers
- Department
of Chemistry, University of Wisconsin—Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States,
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11
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Mitterreiter E, Schuler B, Micevic A, Hernangómez-Pérez D, Barthelmi K, Cochrane KA, Kiemle J, Sigger F, Klein J, Wong E, Barnard ES, Watanabe K, Taniguchi T, Lorke M, Jahnke F, Finley JJ, Schwartzberg AM, Qiu DY, Refaely-Abramson S, Holleitner AW, Weber-Bargioni A, Kastl C. The role of chalcogen vacancies for atomic defect emission in MoS 2. Nat Commun 2021; 12:3822. [PMID: 34158488 PMCID: PMC8219741 DOI: 10.1038/s41467-021-24102-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 05/28/2021] [Indexed: 11/08/2022] Open
Abstract
For two-dimensional (2D) layered semiconductors, control over atomic defects and understanding of their electronic and optical functionality represent major challenges towards developing a mature semiconductor technology using such materials. Here, we correlate generation, optical spectroscopy, atomic resolution imaging, and ab initio theory of chalcogen vacancies in monolayer MoS2. Chalcogen vacancies are selectively generated by in-vacuo annealing, but also focused ion beam exposure. The defect generation rate, atomic imaging and the optical signatures support this claim. We discriminate the narrow linewidth photoluminescence signatures of vacancies, resulting predominantly from localized defect orbitals, from broad luminescence features in the same spectral range, resulting from adsorbates. Vacancies can be patterned with a precision below 10 nm by ion beams, show single photon emission, and open the possibility for advanced defect engineering of 2D semiconductors at the ultimate scale.
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Grants
- EXC 2089/1-390776260 Deutsche Forschungsgemeinschaft (German Research Foundation)
- RTG 2247 Deutsche Forschungsgemeinschaft (German Research Foundation)
- RTG 2247 Deutsche Forschungsgemeinschaft (German Research Foundation)
- DE-AC02-05CH11231 DOE | Office of Science (SC)
- DE-AC02-05CH11231 DOE | Office of Science (SC)
- DE-AC02-05CH11231 DOE | Office of Science (SC)
- DE-AC02-05CH11231 DOE | Office of Science (SC)
- JPMJCR15F3 MEXT | JST | Core Research for Evolutional Science and Technology (CREST)
- JPMJCR15F3 MEXT | JST | Core Research for Evolutional Science and Technology (CREST)
- JPMXP0112101001 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP20H00354 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JPMXP0112101001 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- Nanosystems Initiative Munich (NIM) Bavaria California Technology Center (BaCaTeC)
- Alexander von Humboldt-Stiftung (Alexander von Humboldt Foundation)
- INCITE, Contract No. DE-AC05-00OR22725
- Bavaria California Technology Center (BaCaTeC) TUM International Graduate School of Science and Engineering (IGSSE)
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Affiliation(s)
- Elmar Mitterreiter
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Ana Micevic
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
| | - Daniel Hernangómez-Pérez
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Katja Barthelmi
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
| | | | - Jonas Kiemle
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
| | - Florian Sigger
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
| | - Julian Klein
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Edward Wong
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Edward S Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Michael Lorke
- Bremen Center for Computational Materials Science, University of Bremen, Bremen, Germany
- Bremen Institute for Theoretical Physics, University of Bremen, Bremen, Germany
| | - Frank Jahnke
- Bremen Institute for Theoretical Physics, University of Bremen, Bremen, Germany
| | - Johnathan J Finley
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
| | | | - Diana Y Qiu
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA
| | - Sivan Refaely-Abramson
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Alexander W Holleitner
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany.
- Munich Center for Quantum Science and Technology (MCQST), München, Germany.
| | | | - Christoph Kastl
- Walter Schottky Institut and Physics Department, Technical University of Munich, Garching, Germany.
- Munich Center for Quantum Science and Technology (MCQST), München, Germany.
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12
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Lee K, Utama MIB, Kahn S, Samudrala A, Leconte N, Yang B, Wang S, Watanabe K, Taniguchi T, Altoé MVP, Zhang G, Weber-Bargioni A, Crommie M, Ashby PD, Jung J, Wang F, Zettl A. Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures. Sci Adv 2020; 6:eabd1919. [PMID: 33298449 PMCID: PMC7725474 DOI: 10.1126/sciadv.abd1919] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/22/2020] [Indexed: 05/31/2023]
Abstract
Two-dimensional heterostructures composed of layers with slightly different lattice vectors exhibit new periodic structure known as moiré lattices, which, in turn, can support novel correlated and topological phenomena. Moreover, moiré superstructures can emerge from multiple misaligned moiré lattices or inhomogeneous strain distributions, offering additional degrees of freedom in tailoring electronic structure. High-resolution imaging of the moiré lattices and superstructures is critical for understanding the emerging physics. Here, we report the imaging of moiré lattices and superstructures in graphene-based samples under ambient conditions using an ultrahigh-resolution implementation of scanning microwave impedance microscopy. Although the probe tip has a gross radius of ~100 nm, spatial resolution better than 5 nm is achieved, which allows direct visualization of the structural details in moiré lattices and the composite super-moiré. We also demonstrate artificial synthesis of novel superstructures, including the Kagome moiré arising from the interplay between different layers.
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Affiliation(s)
- Kyunghoon Lee
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - M Iqbal Bakti Utama
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Salman Kahn
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Nicolas Leconte
- Department of Physics, University of Seoul, Seoul, South Korea
| | - Birui Yang
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Shuopei Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - M Virginia P Altoé
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Guangyu Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | | | - Michael Crommie
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Paul D Ashby
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jeil Jung
- Department of Physics, University of Seoul, Seoul, South Korea
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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13
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Kozhakhmetov A, Schuler B, Tan AMZ, Cochrane KA, Nasr JR, El-Sherif H, Bansal A, Vera A, Bojan V, Redwing JM, Bassim N, Das S, Hennig RG, Weber-Bargioni A, Robinson JA. Scalable Substitutional Re-Doping and its Impact on the Optical and Electronic Properties of Tungsten Diselenide. Adv Mater 2020; 32:e2005159. [PMID: 33169451 DOI: 10.1002/adma.202005159] [Citation(s) in RCA: 5] [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] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Reliable, controlled doping of 2D transition metal dichalcogenides will enable the realization of next-generation electronic, logic-memory, and magnetic devices based on these materials. However, to date, accurate control over dopant concentration and scalability of the process remains a challenge. Here, a systematic study of scalable in situ doping of fully coalesced 2D WSe2 films with Re atoms via metal-organic chemical vapor deposition is reported. Dopant concentrations are uniformly distributed over the substrate surface, with precisely controlled concentrations down to <0.001% Re achieved by tuning the precursor partial pressure. Moreover, the impact of doping on morphological, chemical, optical, and electronic properties of WSe2 is elucidated with detailed experimental and theoretical examinations, confirming that the substitutional doping of Re at the W site leads to n-type behavior of WSe2 . Transport characteristics of fabricated back-gated field-effect-transistors are directly correlated to the dopant concentration, with degrading device performances for doping concentrations exceeding 1% of Re. The study demonstrates a viable approach to introducing true dopant-level impurities with high precision, which can be scaled up to batch production for applications beyond digital electronics.
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Affiliation(s)
- Azimkhan Kozhakhmetov
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland
| | - Anne Marie Z Tan
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Katherine A Cochrane
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joseph R Nasr
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hesham El-Sherif
- Department of Materials Science and Engineering, McMaster University, Hamilton, ON, L8S 4L8, Canada
| | - Anushka Bansal
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Alex Vera
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Vincent Bojan
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Joan M Redwing
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nabil Bassim
- Department of Materials Science and Engineering, McMaster University, Hamilton, ON, L8S 4L8, Canada
| | - Saptarshi Das
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Richard G Hennig
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | | | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Two-Dimensional Crystal Consortium, The Pennsylvania State University, University Park, PA, 16802, USA
- Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
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14
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Uddin SZ, Kim H, Lorenzon M, Yeh M, Lien DH, Barnard ES, Htoon H, Weber-Bargioni A, Javey A. Neutral Exciton Diffusion in Monolayer MoS 2. ACS Nano 2020; 14:13433-13440. [PMID: 32909735 DOI: 10.1021/acsnano.0c05305] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Monolayer transition metal dichalcogenides (TMDCs) are promising materials for next generation optoelectronic devices. The exciton diffusion length is a critical parameter that reflects the quality of exciton transport in monolayer TMDCs and limits the performance of many excitonic devices. Although diffusion lengths of a few hundred nanometers have been reported in the literature for as-exfoliated monolayers, these measurements are convoluted by neutral and charged excitons (trions) that coexist at room temperature due to natural background doping. Untangling the diffusion of neutral excitons and trions is paramount to understand the fundamental limits and potential of new optoelectronic device architectures made possible using TMDCs. In this work, we measure the diffusion lengths of neutral excitons and trions in monolayer MoS2 by tuning the background carrier concentration using a gate voltage and utilizing both steady state and transient spectroscopy. We observe diffusion lengths of 1.5 μm and 300 nm for neutral excitons and trions, respectively, at an optical power density of 0.6 W cm-2.
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Affiliation(s)
- Shiekh Zia Uddin
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United State
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Hyungjin Kim
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United State
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Monica Lorenzon
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Matthew Yeh
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United State
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Der-Hsien Lien
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United State
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Edward S Barnard
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Han Htoon
- Center for Integrated Nanotechnologies, Material Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Alexander Weber-Bargioni
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ali Javey
- Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United State
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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15
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Schäfer C, Perera PN, Laible F, Olynick DL, Schwartzberg AM, Weber-Bargioni A, Cabrini S, Schuck PJ, Kern DP, Fleischer M. Selectively accessing the hotspots of optical nanoantennas by self-aligned dry laser ablation. Nanoscale 2020; 12:19170-19177. [PMID: 32926034 DOI: 10.1039/d0nr04024j] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Plasmonic nanostructures serve as optical antennas for concentrating the energy of incoming light in localized hotspots close to their surface. By positioning nanoemitters in the antenna hotspots, energy transfer is enabled, leading to novel hybrid antenna-emitter-systems, where the antenna can be used to manipulate the optical properties of the nano-objects. The challenge remains how to precisely position emitters within the hotspots. We report a self-aligned process based on dry laser ablation of a calixarene that enables the attachment of molecules within the electromagnetic hotspots at the tips of gold nanocones. Within the laser focus, the ablation threshold is exceeded in nanoscale volumes, leading to selective access of the hotspot areas. A first indication of the site-selective functionalization process is given by attaching fluorescently labelled proteins to the nanocones. In a second example, Raman-active molecules are selectively attached only to nanocones that were previously exposed in the laser focus, which is verified by surface enhanced Raman spectroscopy. Enabling selective functionalization is an important prerequisite e.g. for preparing single photon sources for quantum optical technologies, or multiplexed Raman sensing platforms.
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Affiliation(s)
- Christian Schäfer
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Pradeep N Perera
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Florian Laible
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Deirdre L Olynick
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Adam M Schwartzberg
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Alexander Weber-Bargioni
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Stefano Cabrini
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - P James Schuck
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 67, Berkeley, CA 94720, USA
| | - Dieter P Kern
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Monika Fleischer
- Institute for Applied Physics and Center LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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16
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Schuler B, Cochrane KA, Kastl C, Barnard ES, Wong E, Borys NJ, Schwartzberg AM, Ogletree DF, de Abajo FJG, Weber-Bargioni A. Electrically driven photon emission from individual atomic defects in monolayer WS 2. Sci Adv 2020; 6:eabb5988. [PMID: 32938664 PMCID: PMC7494346 DOI: 10.1126/sciadv.abb5988] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/31/2020] [Indexed: 05/22/2023]
Abstract
Quantum dot-like single-photon sources in transition metal dichalcogenides (TMDs) exhibit appealing quantum optical properties but lack a well-defined atomic structure and are subject to large spectral variability. Here, we demonstrate electrically stimulated photon emission from individual atomic defects in monolayer WS2 and directly correlate the emission with the local atomic and electronic structure. Radiative transitions are locally excited by sequential inelastic electron tunneling from a metallic tip into selected discrete defect states in the WS2 bandgap. Coupling to the optical far field is mediated by tip plasmons, which transduce the excess energy into a single photon. The applied tip-sample voltage determines the transition energy. Atomically resolved emission maps of individual point defects closely resemble electronic defect orbitals, the final states of the optical transitions. Inelastic charge carrier injection into localized defect states of two-dimensional materials provides a powerful platform for electrically driven, broadly tunable, atomic-scale single-photon sources.
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Affiliation(s)
- Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, CA 94720, USA.
| | | | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, CA 94720, USA
- Walter-Schottky-Institut and Physik-Department, Technical University of Munich, Garching 85748, Germany
| | - Edward S Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, CA 94720, USA
| | - Edward Wong
- Molecular Foundry, Lawrence Berkeley National Laboratory, CA 94720, USA
| | - Nicholas J Borys
- Molecular Foundry, Lawrence Berkeley National Laboratory, CA 94720, USA
- Department of Physics, Montana State University, Bozeman, MT 59717, USA
| | | | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, CA 94720, USA
| | - F Javier García de Abajo
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain.
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
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17
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Penzo E, Loiudice A, Barnard ES, Borys NJ, Jurow MJ, Lorenzon M, Rajzbaum I, Wong EK, Liu Y, Schwartzberg AM, Cabrini S, Whitelam S, Buonsanti R, Weber-Bargioni A. Long-Range Exciton Diffusion in Two-Dimensional Assemblies of Cesium Lead Bromide Perovskite Nanocrystals. ACS Nano 2020; 14:6999-7007. [PMID: 32459460 DOI: 10.1021/acsnano.0c01536] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [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
Förster resonant energy transfer (FRET)-mediated exciton diffusion through artificial nanoscale building block assemblies could be used as an optoelectronic design element to transport energy. However, so far, nanocrystal (NC) systems supported only diffusion lengths of 30 nm, which are too small to be useful in devices. Here, we demonstrate a FRET-mediated exciton diffusion length of 200 nm with 0.5 cm2/s diffusivity through an ordered, two-dimensional assembly of cesium lead bromide perovskite nanocrystals (CsPbBr3 PNCs). Exciton diffusion was directly measured via steady-state and time-resolved photoluminescence (PL) microscopy, with physical modeling providing deeper insight into the transport process. This exceptionally efficient exciton transport is facilitated by PNCs' high PL quantum yield, large absorption cross section, and high polarizability, together with minimal energetic and geometric disorder of the assembly. This FRET-mediated exciton diffusion length matches perovskites' optical absorption depth, thus enabling the design of device architectures with improved performances and providing insight into the high conversion efficiencies of PNC-based optoelectronic devices.
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Affiliation(s)
- Erika Penzo
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Anna Loiudice
- Institute of Chemical Sciences and Engineering of the École Polytechnique Fédérale de Lausanne, Lausanne CH 1015, Switzerland
| | - Edward S Barnard
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Nicholas J Borys
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Matthew J Jurow
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Monica Lorenzon
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Igor Rajzbaum
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Edward K Wong
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Yi Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Adam M Schwartzberg
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Stefano Cabrini
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Stephen Whitelam
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Raffaella Buonsanti
- Institute of Chemical Sciences and Engineering of the École Polytechnique Fédérale de Lausanne, Lausanne CH 1015, Switzerland
| | - Alexander Weber-Bargioni
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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18
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Mitterreiter E, Schuler B, Cochrane KA, Wurstbauer U, Weber-Bargioni A, Kastl C, Holleitner AW. Atomistic Positioning of Defects in Helium Ion Treated Single-Layer MoS 2. Nano Lett 2020; 20:4437-4444. [PMID: 32368920 DOI: 10.1021/acs.nanolett.0c01222] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [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
Structuring materials with atomic precision is the ultimate goal of nanotechnology and is becoming increasingly relevant as an enabling technology for quantum electronics/spintronics and quantum photonics. Here, we create atomic defects in monolayer MoS2 by helium ion (He-ion) beam lithography with a spatial fidelity approaching the single-atom limit in all three dimensions. Using low-temperature scanning tunneling microscopy (STM), we confirm the formation of individual point defects in MoS2 upon He-ion bombardment and show that defects are generated within 9 nm of the incident helium ions. Atom-specific sputtering yields are determined by analyzing the type and occurrence of defects observed in high-resolution STM images and compared with Monte Carlo simulations. Both theory and experiment indicate that the He-ion bombardment predominantly generates sulfur vacancies.
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Affiliation(s)
- Elmar Mitterreiter
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Katherine A Cochrane
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Ursula Wurstbauer
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Institute of Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str.10, 48149 Münster, Germany
| | - Alexander Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Christoph Kastl
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Alexander W Holleitner
- Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 München, Germany
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19
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Li H, Utama MIB, Wang S, Zhao W, Zhao S, Xiao X, Jiang Y, Jiang L, Taniguchi T, Watanabe K, Weber-Bargioni A, Zettl A, Wang F. Global Control of Stacking-Order Phase Transition by Doping and Electric Field in Few-Layer Graphene. Nano Lett 2020; 20:3106-3112. [PMID: 32286843 DOI: 10.1021/acs.nanolett.9b05092] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [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
The layer stacking order has profound effects on the physical properties of two-dimensional van der Waals heterostructures. For example, graphene multilayers can have distinct electronic band structures and exhibit completely different behaviors depending on the stacking order. Fascinating physical phenomena, such as correlated insulators, superconductors, and ferromagnetism, can also emerge with a periodic variation of the layer stacking order, which is known as the moiré superlattice in van der Waals materials. In this work, we realize the global phase transition between different graphene layer stacking orders and elucidate its microscopic origin. We experimentally determine the energy difference between different stacking orders with the accuracy of μeV/atom. We reveal that both the carrier doping and the electric field can drive the layer-stacking phase transition through different mechanisms: carrier doping can change the energy difference because of a non-negligible work function difference between different stacking orders; the electric field, on the other hand, induces a band-gap opening in ABC-stacked graphene and hence changes the energy difference. Our findings provide a fundamental understanding of the electrically driven stacking-order phase transition in few-layer graphene and demonstrate a reversible and noninvasive method to globally control the stacking order.
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Affiliation(s)
- Hongyuan Li
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - M Iqbal Bakti Utama
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, United States
| | - Sheng Wang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Wenyu Zhao
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Sihan Zhao
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Xiao Xiao
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yue Jiang
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Lili Jiang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | | | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Alexander Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy Nano Sciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy Nano Sciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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20
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Schuler B, Lee JH, Kastl C, Cochrane KA, Chen CT, Refaely-Abramson S, Yuan S, van Veen E, Roldán R, Borys NJ, Koch RJ, Aloni S, Schwartzberg AM, Ogletree DF, Neaton JB, Weber-Bargioni A. How Substitutional Point Defects in Two-Dimensional WS 2 Induce Charge Localization, Spin-Orbit Splitting, and Strain. ACS Nano 2019; 13:10520-10534. [PMID: 31393700 DOI: 10.1021/acsnano.9b04611] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Control of impurity concentrations in semiconducting materials is essential to device technology. Because of their intrinsic confinement, the properties of two-dimensional semiconductors such as transition metal dichalcogenides (TMDs) are more sensitive to defects than traditional bulk materials. The technological adoption of TMDs is dependent on the mitigation of deleterious defects and guided incorporation of functional foreign atoms. The first step toward impurity control is the identification of defects and assessment of their electronic properties. Here, we present a comprehensive study of point defects in monolayer tungsten disulfide (WS2) grown by chemical vapor deposition using scanning tunneling microscopy/spectroscopy, CO-tip noncontact atomic force microscopy, Kelvin probe force spectroscopy, density functional theory, and tight-binding calculations. We observe four different substitutional defects: chromium (CrW) and molybdenum (MoW) at a tungsten site, oxygen at sulfur sites in both top and bottom layers (OS top/bottom), and two negatively charged defects (CD type I and CD type II). Their electronic fingerprints unambiguously corroborate the defect assignment and reveal the presence or absence of in-gap defect states. CrW forms three deep unoccupied defect states, two of which arise from spin-orbit splitting. The formation of such localized trap states for CrW differs from the MoW case and can be explained by their different d shell energetics and local strain, which we directly measured. Utilizing a tight-binding model the electronic spectra of the isolectronic substitutions OS and CrW are mimicked in the limit of a zero hopping term and infinite on-site energy at a S and W site, respectively. The abundant CDs are negatively charged, which leads to a significant band bending around the defect and a local increase of the contact potential difference. In addition, CD-rich domains larger than 100 nm are observed, causing a work function increase of 1.1 V. While most defects are electronically isolated, we also observed hybrid states formed between CrW dimers. The important role of charge localization, spin-orbit coupling, and strain for the formation of deep defect states observed at substitutional defects in WS2 as reported here will guide future efforts of targeted defect engineering and doping of TMDs.
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Affiliation(s)
- Bruno Schuler
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Jun-Ho Lee
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Physics , University of California at Berkeley , Berkeley , California 94720 , United States
| | - Christoph Kastl
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Walter-Schottky-Institut and Physik-Department , Technical University of Munich , Garching 85748 , Germany
| | - Katherine A Cochrane
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Christopher T Chen
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Sivan Refaely-Abramson
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Materials and Interfaces , Weizmann Institute of Science , Rehovot 7610001 , Israel
| | - Shengjun Yuan
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Edo van Veen
- Radboud University of Nijmegen , Institute for Molecules and Materials , Heijendaalseweg 135 , 6525 AJ , Nijmegen , The Netherlands
| | - Rafael Roldán
- Instituto de Ciencia de Materiales de Madrid , ICMM-CSIC, Cantoblanco, E-28049 , Madrid , Spain
| | - Nicholas J Borys
- Department of Physics , Montana State University , Bozeman , Montana 59717 , United States
| | - Roland J Koch
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Shaul Aloni
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Adam M Schwartzberg
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - D Frank Ogletree
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Jeffrey B Neaton
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Physics , University of California at Berkeley , Berkeley , California 94720 , United States
- Kavli Energy Nanosciences Institute at Berkeley , Berkeley , California 94720 , United States
| | - Alexander Weber-Bargioni
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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21
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Schuler B, Qiu DY, Refaely-Abramson S, Kastl C, Chen CT, Barja S, Koch RJ, Ogletree DF, Aloni S, Schwartzberg AM, Neaton JB, Louie SG, Weber-Bargioni A. Large Spin-Orbit Splitting of Deep In-Gap Defect States of Engineered Sulfur Vacancies in Monolayer WS_{2}. Phys Rev Lett 2019; 123:076801. [PMID: 31491121 DOI: 10.1103/physrevlett.123.076801] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/29/2019] [Indexed: 06/10/2023]
Abstract
Structural defects in 2D materials offer an effective way to engineer new material functionalities beyond conventional doping. We report on the direct experimental correlation of the atomic and electronic structure of a sulfur vacancy in monolayer WS_{2} by a combination of CO-tip noncontact atomic force microscopy and scanning tunneling microscopy. Sulfur vacancies, which are absent in as-grown samples, were deliberately created by annealing in vacuum. Two energetically narrow unoccupied defect states followed by vibronic sidebands provide a unique fingerprint of this defect. Direct imaging of the defect orbitals, together with ab initio GW calculations, reveal that the large splitting of 252±4 meV between these defect states is induced by spin-orbit coupling.
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Affiliation(s)
- Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sivan Refaely-Abramson
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Walter Schottky Institute and Physics Department, Technical University of Munich, 85748 Garching, Germany
| | - Christopher T Chen
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sara Barja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián 20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao 48013, Spain
- Donostia International Physics Center, Donostia-San Sebastin 20018, Spain
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Adam M Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Kavli Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, USA
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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22
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Barja S, Refaely-Abramson S, Schuler B, Qiu DY, Pulkin A, Wickenburg S, Ryu H, Ugeda MM, Kastl C, Chen C, Hwang C, Schwartzberg A, Aloni S, Mo SK, Frank Ogletree D, Crommie MF, Yazyev OV, Louie SG, Neaton JB, Weber-Bargioni A. Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides. Nat Commun 2019; 10:3382. [PMID: 31358753 PMCID: PMC6662818 DOI: 10.1038/s41467-019-11342-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [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: 02/14/2019] [Accepted: 07/05/2019] [Indexed: 12/24/2022] Open
Abstract
Chalcogen vacancies are generally considered to be the most common point defects in transition metal dichalcogenide (TMD) semiconductors because of their low formation energy in vacuum and their frequent observation in transmission electron microscopy studies. Consequently, unexpected optical, transport, and catalytic properties in 2D-TMDs have been attributed to in-gap states associated with chalcogen vacancies, even in the absence of direct experimental evidence. Here, we combine low-temperature non-contact atomic force microscopy, scanning tunneling microscopy and spectroscopy, and state-of-the-art ab initio density functional theory and GW calculations to determine both the atomic structure and electronic properties of an abundant chalcogen-site point defect common to MoSe2 and WS2 monolayers grown by molecular beam epitaxy and chemical vapor deposition, respectively. Surprisingly, we observe no in-gap states. Our results strongly suggest that the common chalcogen defects in the described 2D-TMD semiconductors, measured in vacuum environment after gentle annealing, are oxygen substitutional defects, rather than vacancies.
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Affiliation(s)
- Sara Barja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, 20018, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain.
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain.
| | - Sivan Refaely-Abramson
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Artem Pulkin
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Sebastian Wickenburg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Miguel M Ugeda
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
| | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Christopher Chen
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan, 46241, Korea
| | - Adam Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, 94720, USA
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, 94720, USA.
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, 94720, USA.
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23
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Miscuglio M, Borys NJ, Spirito D, Martín-García B, Zaccaria RP, Weber-Bargioni A, Schuck PJ, Krahne R. Planar Aperiodic Arrays as Metasurfaces for Optical Near-Field Patterning. ACS Nano 2019; 13:5646-5654. [PMID: 31021592 DOI: 10.1021/acsnano.9b00821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [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
Plasmonic metasurfaces have spawned the field of flat optics using nanostructured planar metallic or dielectric surfaces that can replace bulky optical elements and enhance the capabilities of traditional far-field optics. Furthermore, the potential of flat optics can go far beyond far-field modulation and can be exploited for functionality in the near-field itself. Here, we design metasurfaces based on aperiodic arrays of plasmonic Au nanostructures for tailoring the optical near-field in the visible and near-infrared spectral range. The basic element of the arrays is a rhomboid that is modulated in size, orientation, and position to achieve the desired functionality of the micron-size metasurface structure. Using two-photon-photoluminescence as a tool to probe the near-field profiles in the plane of the metasurfaces, we demonstrate the molding of light into different near-field intensity patterns and active pattern control via the far-field illumination. Finite element method simulations reveal that the near-field modulation occurs via a combination of the plasmonic resonances of the rhomboids and field enhancement in the nanoscale gaps in between the elements. This approach enables optical elements that can switch the near-field distribution across the metasurface via wavelength and polarization of the incident far-field light and provides pathways for light matter interaction in integrated devices.
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Affiliation(s)
- Mario Miscuglio
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
- Dipartimento di Chimica e Chimica Industriale , Università degli Studi di Genova , Via Dodecaneso, 31 , 16146 Genova , Italy
| | - Nicholas J Borys
- Molecular Foundry , Lawrence Berkeley National Lab , 1 Cyclotron Road , Berkeley , California 94720 , United States
| | - Davide Spirito
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
| | | | | | - Alexander Weber-Bargioni
- Molecular Foundry , Lawrence Berkeley National Lab , 1 Cyclotron Road , Berkeley , California 94720 , United States
| | - P James Schuck
- Molecular Foundry , Lawrence Berkeley National Lab , 1 Cyclotron Road , Berkeley , California 94720 , United States
| | - Roman Krahne
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
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24
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Kastl C, Koch RJ, Chen CT, Eichhorn J, Ulstrup S, Bostwick A, Jozwiak C, Kuykendall TR, Borys NJ, Toma FM, Aloni S, Weber-Bargioni A, Rotenberg E, Schwartzberg AM. Effects of Defects on Band Structure and Excitons in WS 2 Revealed by Nanoscale Photoemission Spectroscopy. ACS Nano 2019; 13:1284-1291. [PMID: 30645100 DOI: 10.1021/acsnano.8b06574] [Citation(s) in RCA: 9] [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: 06/09/2023]
Abstract
Two-dimensional materials with engineered composition and structure will provide designer materials beyond conventional semiconductors. However, the potentials of defect engineering remain largely untapped, because it hinges on a precise understanding of electronic structure and excitonic properties, which are not yet predictable by theory alone. Here, we utilize correlative, nanoscale photoemission spectroscopy to visualize how local introduction of defects modifies electronic and excitonic properties of two-dimensional materials at the nanoscale. As a model system, we study chemical vapor deposition grown monolayer WS2, a prototypical, direct gap, two-dimensional semiconductor. By cross-correlating nanoscale angle-resolved photoemission spectroscopy, core level spectroscopy, and photoluminescence, we unravel how local variations in defect density influence electronic structure, lateral band alignment, and excitonic phenomena in synthetic WS2 monolayers.
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Affiliation(s)
- Christoph Kastl
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Roland J Koch
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Christopher T Chen
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Johanna Eichhorn
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Søren Ulstrup
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , 8000 Aarhus C, Denmark
| | - Aaron Bostwick
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Chris Jozwiak
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Tevye R Kuykendall
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Nicholas J Borys
- Department of Physics , Montana State University , Bozeman , Montana 59717 , United States
| | - Francesca M Toma
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Shaul Aloni
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Alexander Weber-Bargioni
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Eli Rotenberg
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Adam M Schwartzberg
- The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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25
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Borys NJ, Barnard ES, Gao S, Yao K, Bao W, Buyanin A, Zhang Y, Tongay S, Ko C, Suh J, Weber-Bargioni A, Wu J, Yang L, Schuck PJ. Anomalous Above-Gap Photoexcitations and Optical Signatures of Localized Charge Puddles in Monolayer Molybdenum Disulfide. ACS Nano 2017; 11:2115-2123. [PMID: 28117983 DOI: 10.1021/acsnano.6b08278] [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: 06/06/2023]
Abstract
Broadband optoelectronics such as artificial light harvesting technologies necessitate efficient and, ideally, tunable coupling of excited states over a wide range of energies. In monolayer MoS2, a prototypical two-dimensional layered semiconductor, the excited state manifold spans the visible electromagnetic spectrum and is comprised of an interconnected network of excitonic and free-carrier excitations. Here, photoluminescence excitation spectroscopy is used to reveal the energetic and spatial dependence of broadband excited state coupling to the ground-state luminescent excitons of monolayer MoS2. Photoexcitation of the direct band gap excitons is found to strengthen with increasing energy, demonstrating that interexcitonic coupling across the Brillouin zone is more efficient than previously reported, and thus bolstering the import and appeal of these materials for broadband optoelectronic applications. Narrow excitation resonances that are superimposed on the broadband photoexcitation spectrum are identified and coincide with the energetic positions of the higher-energy excitons and the electronic band gap as predicted by first-principles calculations. Identification of such features outlines a facile route to measure the optical and electronic band gaps and thus the exciton binding energy in the more sophisticated device architectures that are necessary for untangling the rich many-body phenomena and complex photophysics of these layered semiconductors. In as-grown materials, the excited states exhibit microscopic spatial variations that are characteristic of local carrier density fluctuations, similar to charge puddling phenomena in graphene. Such variations likely arise from substrate inhomogeneity and demonstrate the possibility to use substrate patterning to tune local carrier density and dynamically control excited states for designer optoelectronics.
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Affiliation(s)
| | | | - Shiyuan Gao
- Department of Physics, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | | | - Wei Bao
- Department of Materials Science and Engineering, University of California Berkeley , Berkeley, California 94720, United States
| | | | | | - Sefaattin Tongay
- Department of Materials Science and Engineering, University of California Berkeley , Berkeley, California 94720, United States
- Department of Materials Science and Engineering, Arizona State University , Tempe, Arizona 85287, United States
| | - Changhyun Ko
- Department of Materials Science and Engineering, University of California Berkeley , Berkeley, California 94720, United States
| | - Joonki Suh
- Department of Materials Science and Engineering, University of California Berkeley , Berkeley, California 94720, United States
| | | | - Junqiao Wu
- Department of Materials Science and Engineering, University of California Berkeley , Berkeley, California 94720, United States
| | - Li Yang
- Department of Physics, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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26
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Paraskevaidis C, Kuykendall T, Melli M, Weber-Bargioni A, Schuck PJ, Schwartzberg A, Dhuey S, Cabrini S, Grebel H. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas. Nanoscale 2015; 7:15321-15331. [PMID: 26332298 DOI: 10.1039/c5nr03893f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve.
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27
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Bao W, Borys NJ, Ko C, Suh J, Fan W, Thron A, Zhang Y, Buyanin A, Zhang J, Cabrini S, Ashby PD, Weber-Bargioni A, Tongay S, Aloni S, Ogletree DF, Wu J, Salmeron MB, Schuck PJ. Visualizing nanoscale excitonic relaxation properties of disordered edges and grain boundaries in monolayer molybdenum disulfide. Nat Commun 2015; 6:7993. [PMID: 26269394 PMCID: PMC4557266 DOI: 10.1038/ncomms8993] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/03/2015] [Indexed: 01/04/2023] Open
Abstract
Two-dimensional monolayer transition metal dichalcogenide semiconductors are ideal building blocks for atomically thin, flexible optoelectronic and catalytic devices. Although challenging for two-dimensional systems, sub-diffraction optical microscopy provides a nanoscale material understanding that is vital for optimizing their optoelectronic properties. Here we use the ‘Campanile' nano-optical probe to spectroscopically image exciton recombination within monolayer MoS2 with sub-wavelength resolution (60 nm), at the length scale relevant to many critical optoelectronic processes. Synthetic monolayer MoS2 is found to be composed of two distinct optoelectronic regions: an interior, locally ordered but mesoscopically heterogeneous two-dimensional quantum well and an unexpected ∼300-nm wide, energetically disordered edge region. Further, grain boundaries are imaged with sufficient resolution to quantify local exciton-quenching phenomena, and complimentary nano-Auger microscopy reveals that the optically defective grain boundary and edge regions are sulfur deficient. The nanoscale structure–property relationships established here are critical for the interpretation of edge- and boundary-related phenomena and the development of next-generation two-dimensional optoelectronic devices. Understanding the dynamics of light-induced carriers is vital for employing two-dimensional materials in optoelectronic applications. Here, the authors use a sub diffraction-limit optical technique to reveal the excitonic properties of monolayer molybdenum disulfide at the nanoscale.
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Affiliation(s)
- Wei Bao
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [3] Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - Nicholas J Borys
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Changhyun Ko
- Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - Joonki Suh
- Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - Wen Fan
- Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - Andrew Thron
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Yingjie Zhang
- 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Applied Science and Technology Graduate Program, University of California, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - Alexander Buyanin
- 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Department of Chemistry, University of California Berkeley, 419 Latimer Hall, Berkeley, California 94720, USA
| | - Jie Zhang
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Stefano Cabrini
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Paul D Ashby
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Alexander Weber-Bargioni
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Sefaattin Tongay
- 1] Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, Arizona State University, P.O. Box 876106, Tempe, Arizona 85287, USA
| | - Shaul Aloni
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - D Frank Ogletree
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Junqiao Wu
- 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - Miquel B Salmeron
- 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, University of California Berkeley, 210 Hearst Mining Building, Berkeley, California 94720, USA
| | - P James Schuck
- 1] Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
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28
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Caselli N, La China F, Bao W, Riboli F, Gerardino A, Li L, Linfield EH, Pagliano F, Fiore A, Schuck PJ, Cabrini S, Weber-Bargioni A, Gurioli M, Intonti F. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna. Sci Rep 2015; 5:9606. [PMID: 26045401 PMCID: PMC4456763 DOI: 10.1038/srep09606] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/10/2015] [Indexed: 11/09/2022] Open
Abstract
Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.
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Affiliation(s)
- Niccolò Caselli
- 1] European Laboratory for Non-linear Spectroscopy, 50019 Sesto Fiorentino (FI), Italy [2] Department of Physics, University of Florence, 50019 Sesto Fiorentino (FI), Italy
| | - Federico La China
- 1] European Laboratory for Non-linear Spectroscopy, 50019 Sesto Fiorentino (FI), Italy [2] Department of Physics, University of Florence, 50019 Sesto Fiorentino (FI), Italy
| | - Wei Bao
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Francesco Riboli
- Department of Physics, University of Trento, via Sommarive 14, 38123, Povo (TN), Italy
| | | | - Lianhe Li
- School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Edmund H Linfield
- School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Francesco Pagliano
- COBRA Research Institute, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Andrea Fiore
- COBRA Research Institute, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - P James Schuck
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Stefano Cabrini
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Massimo Gurioli
- 1] European Laboratory for Non-linear Spectroscopy, 50019 Sesto Fiorentino (FI), Italy [2] Department of Physics, University of Florence, 50019 Sesto Fiorentino (FI), Italy
| | - Francesca Intonti
- 1] European Laboratory for Non-linear Spectroscopy, 50019 Sesto Fiorentino (FI), Italy [2] Department of Physics, University of Florence, 50019 Sesto Fiorentino (FI), Italy
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29
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Lee J, Bao W, Ju L, Schuck PJ, Wang F, Weber-Bargioni A. Switching individual quantum dot emission through electrically controlling resonant energy transfer to graphene. Nano Lett 2014; 14:7115-7119. [PMID: 25383700 DOI: 10.1021/nl503587z] [Citation(s) in RCA: 13] [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] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Electrically controlling resonant energy transfer of optical emitters provides a novel mechanism to switch nanoscale light sources on and off individually for optoelectronic applications. Graphene's optical transitions are tunable through electrostatic gating over a broad wavelength spectrum, making it possible to modulate energy transfer from a variety of nanoemitters to graphene at room temperature. We demonstrate photoluminescence switching of individual colloidal quantum dots by electrically tuning their energy transfer to graphene. The gate dependence of energy transfer modulation confirms that the transition occurs when the Fermi level is shifted over half the emitter's excitation energy. The modulation magnitude decreases rapidly with increasing emitter-graphene distance (d), following the 1/d(4) rate trend unique to the energy transfer process to two-dimensional materials.
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Affiliation(s)
- Jiye Lee
- Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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30
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Salmistraro M, Schwartzberg A, Bao W, Depero LE, Weber-Bargioni A, Cabrini S, Alessandri I. Triggering and monitoring plasmon-enhanced reactions by optical nanoantennas coupled to photocatalytic beads. Small 2013; 9:3301-3307. [PMID: 23606587 DOI: 10.1002/smll.201300211] [Citation(s) in RCA: 12] [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] [Received: 01/21/2013] [Indexed: 06/02/2023]
Abstract
Plasmonic metal/semiconductor nanocomposites promise to be a breakthrough for boosting and investigating photon-assisted processes at the nanoscale, with exciting perspectives for energy conversion and catalysis. However, the efficiency and selectivity of these surface processes are still far from being controlled. Here, shown for the first time, is a new class of photocatalyst which is based on the synergistic combination of bowtie-like gold nanoantennas and SiO2 /TiO2 core/shell oxide beads. These systems are exploited as efficient near-field optical light concentrators, stimulating photon-driven processes at the metal-semiconductor interface. Extraordinary enhancements of photodegradation rates (minutes instead of hours) result from matching the nanoantenna surface plasmon resonance with the optical absorption of organic dyes and the excitation source wavelength. Moreover, strong Raman enhancements are observed allowing for direct in-situ monitoring of reaction progress of different analytes on the same site.
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Affiliation(s)
- Marco Salmistraro
- INSTM and Chemistry for Technologies Lab., University of Brescia, via Branze 38, 25123 Brescia, Italy
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31
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Schäfer C, Gollmer DA, Horrer A, Fulmes J, Weber-Bargioni A, Cabrini S, Schuck PJ, Kern DP, Fleischer M. A single particle plasmon resonance study of 3D conical nanoantennas. Nanoscale 2013; 5:7861-7866. [PMID: 23846476 DOI: 10.1039/c3nr01292a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Metallic nanocones are well-suited optical antennas for near-field microscopy and spectroscopy, exhibiting a number of different plasmonic modes. A major challenge in using nanocones for many applications is maximizing the signal at the tip while minimizing the background from the base. It is shown that nanocone plasmon resonance properties can be shifted over a wide range of wavelengths by variation of the substrate, material, size and shape, enabling potential control over specific modes and field distributions. The individual resonances are identified and studied by correlated single particle dark field scattering and scanning electron microscopy in combination with numerical simulations.
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Affiliation(s)
- Christian Schäfer
- Eberhard Karls Universität Tübingen, Institute for Applied Physics and Center LISA+, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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32
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Melli M, Polyakov A, Gargas D, Huynh C, Scipioni L, Bao W, Ogletree DF, Schuck PJ, Cabrini S, Weber-Bargioni A. Reaching the theoretical resonance quality factor limit in coaxial plasmonic nanoresonators fabricated by helium ion lithography. Nano Lett 2013; 13:2687-2691. [PMID: 23617768 DOI: 10.1021/nl400844a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Optical antenna structures have revolutionized the field of nano-optics by confining light to deep subwavelength dimensions for spectroscopy and sensing. In this work, we fabricated coaxial optical antennae with sub-10-nanometer critical dimensions using helium ion lithography (HIL). Wavelength dependent transmission measurements were used to determine the wavelength-dependent optical response. The quality factor of 11 achieved with our HIL fabricated structures matched the theoretically predicted quality factor for the idealized flawless gold resonators calculated by finite-difference time-domain (FDTD). For comparison, coaxial antennae with 30 nm critical dimensions were fabricated using both HIL and the more common Ga focus ion beam lithography (Ga-FIB). The quality factor of the Ga-FIB resonators was 60% of the ideal HIL results for the same design geometry due to limitations in the Ga-FIB fabrication process.
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Affiliation(s)
- M Melli
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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33
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Bao W, Staffaroni M, Bokor J, Salmeron MB, Yablonovitch E, Cabrini S, Weber-Bargioni A, Schuck PJ. Plasmonic near-field probes: a comparison of the campanile geometry with other sharp tips. Opt Express 2013; 21:8166-8176. [PMID: 23571906 DOI: 10.1364/oe.21.008166] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Efficient conversion of photonic to plasmonic energy is important for nano-optical applications, particularly imaging and spectroscopy. Recently a new generation of photonic/plasmonic transducers, the 'campanile' probes, has been developed that overcomes many shortcomings of previous near-field probes by efficiently merging broadband field enhancement with bidirectional coupling of far- to near-field electromagnetic modes. In this work we compare the properties of the campanile structure with those of current NSOM tips using finite element simulations. Field confinement, enhancement, and polarization near the apex of the probe are evaluated relative to local fields created by conical tapered tips in vacuum and in tip-substrate gap mode. We show that the campanile design has similar field enhancement and bandwidth capabilities as those of ultra-sharp metallized tips, but without the substrate and sample restrictions inherent in the tip-surface gap mode operation often required by those tips. In addition, we show for the first time that this campanile probe structure also significantly enhances the radiative rate of any dipole emitter located near the probe apex, quantifying the enhanced decay rate and demonstrating that over 90% of the light radiated by the emitter is "captured" by this probe. This is equivalent to collecting the light from a solid angle of ~3.6 pi. These advantages are crucial for performing techniques such as Raman and IR spectroscopy, white-light nano-ellipsometry and ultrafast pump-probe studies at the nanoscale.
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Affiliation(s)
- Wei Bao
- Molecular Foundry, Lawrence Berkeley National Lab, One Cyclotron Road, Berkeley, CA 94720, USA
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34
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Bao W, Melli M, Caselli N, Riboli F, Wiersma DS, Staffaroni M, Choo H, Ogletree DF, Aloni S, Bokor J, Cabrini S, Intonti F, Salmeron MB, Yablonovitch E, Schuck PJ, Weber-Bargioni A. Mapping Local Charge Recombination Heterogeneity by Multidimensional Nanospectroscopic Imaging. Science 2012; 338:1317-21. [DOI: 10.1126/science.1227977] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Wei Bao
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - M. Melli
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - N. Caselli
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Firenze, Italy
| | - F. Riboli
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Firenze, Italy
| | - D. S. Wiersma
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Istituto Nazionale di Ottica (CNR-INO), 50125 Firenze, Italy
| | - M. Staffaroni
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720–1770, USA
| | - H. Choo
- Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - D. F. Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - S. Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J. Bokor
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720–1770, USA
| | - S. Cabrini
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - F. Intonti
- European Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Firenze, Italy
- Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Firenze, Italy
| | - M. B. Salmeron
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - E. Yablonovitch
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720–1770, USA
| | - P. J. Schuck
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - A. Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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35
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Fleischer M, Weber-Bargioni A, Altoe MVP, Schwartzberg AM, Schuck PJ, Cabrini S, Kern DP. Gold nanocone near-field scanning optical microscopy probes. ACS Nano 2011; 5:2570-2579. [PMID: 21401116 DOI: 10.1021/nn102199u] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Near-field scanning optical microscopy enables the simultaneous topographical and subdiffraction limited optical imaging of surfaces. A process is presented for the implementation of single individually engineered gold cones at the tips of atomic force microscopy cantilevers. These cantilevers act as novel high-performance optical near-field probes. In the fabrication, thin-film metallization, electron beam induced deposition of etch masks, and Ar ion milling are combined. The cone constitutes a well-defined highly efficient optical antenna with a tip radius on the order of 10 nm and an adjustable plasmon resonance frequency. The sharp tip enables high resolution topographical imaging. By controllably varying the cone size, the resonance frequency can be adapted to the application of choice. Structural properties of these sharp-tipped probes are presented together with topographical images recorded with a cone probe. The antenna functionality is demonstrated by gathering the near-field enhanced Raman signature of individual carbon nanotubes with a gold cone scanning probe.
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Affiliation(s)
- Monika Fleischer
- Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
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Weber-Bargioni A, Schwartzberg A, Cornaglia M, Ismach A, Urban JJ, Pang Y, Gordon R, Bokor J, Salmeron MB, Ogletree DF, Ashby P, Cabrini S, Schuck PJ. Hyperspectral nanoscale imaging on dielectric substrates with coaxial optical antenna scan probes. Nano Lett 2011; 11:1201-1207. [PMID: 21261258 DOI: 10.1021/nl104163m] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have demonstrated hyperspectral tip-enhanced Raman imaging on dielectric substrates using linearly polarized light and nanofabricated coaxial antenna tips. A full Raman spectrum was acquired at each pixel of a 256 by 256 pixel contact-mode atomic force microscope image of carbon nanotubes grown on a fused silica microscope coverslip, allowing D and G mode intensity and D-mode peak shifts to be measured with ∼20 nm spatial resolution. Tip enhancement was sufficient to acquire useful Raman spectra in 50-100 ms. Coaxial scan probes combine the efficiency and enhanced, ultralocalized optical fields of plasmonically coupled antennae with the superior topographical imaging properties of sharp metal tips. The yield of the coaxial tip fabrication process is close to 100%, and the tips are sufficiently durable to support hours of contact-mode force microscope imaging. Our coaxial probes avoid the limitations associated with the "gap-mode" imaging geometry used in most tip-enhanced Raman studies to date, where a sharp metal tip is held ∼1 nm above a metallic substrate with the sample located in the gap.
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Affiliation(s)
- Alexander Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory , One Cyclotron Road, Berkeley, California 94720, United States.
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37
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McLeod A, Weber-Bargioni A, Zhang Z, Dhuey S, Harteneck B, Neaton JB, Cabrini S, Schuck PJ. Nonperturbative visualization of nanoscale plasmonic field distributions via photon localization microscopy. Phys Rev Lett 2011; 106:037402. [PMID: 21405296 DOI: 10.1103/physrevlett.106.037402] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 12/10/2010] [Indexed: 05/30/2023]
Abstract
We demonstrate the nonperturbative use of diffraction-limited optics and photon localization microscopy to visualize the controlled nanoscale shifts of zeptoliter mode volumes within plasmonic nanostructures. Unlike tip- or coating-based methods for mapping near fields, these measurements do not affect the electromagnetic properties of the structure being investigated. We quantify the local field manipulation capabilities of asymmetric bowtie antennas, in agreement with theoretical calculations. The photon-limited localization accuracy of nanoscale mode positions is determined for many of the measured devices to be within a 95% confidence interval of +/-2.5 nm. This accuracy also enables us to characterize the effects of nm-scale fabrication irregularities on local plasmonic mode distributions.
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Affiliation(s)
- A McLeod
- Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
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38
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Seufert K, Bocquet ML, Auwärter W, Weber-Bargioni A, Reichert J, Lorente N, Barth JV. Cis-dicarbonyl binding at cobalt and iron porphyrins with saddle-shape conformation. Nat Chem 2011; 3:114-9. [PMID: 21258383 DOI: 10.1038/nchem.956] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 11/25/2010] [Indexed: 11/09/2022]
Abstract
Diatomic molecules attached to complexed iron or cobalt centres are important in many biological processes. In natural systems, metallotetrapyrrole units carry respiratory gases or provide sensing and catalytic functions. Conceiving synthetic model systems strongly helps to determine the pertinent chemical foundations for such processes, with recent work highlighting the importance of the prosthetic groups' conformational flexibility as an intricate variable affecting their functional properties. Here, we present simple model systems to investigate, at the single molecule level, the interaction of carbon monoxide with saddle-shaped iron- and cobalt-porphyrin conformers, which have been stabilized as two-dimensional arrays on well-defined surfaces. Using scanning tunnelling microscopy we identified a novel bonding scheme expressed in tilted monocarbonyl and cis-dicarbonyl configurations at the functional metal-macrocycle unit. Modelling with density functional theory revealed that the weakly bonded diatomic carbonyl adduct can effectively bridge specific pyrrole groups with the metal atom as a result of the pronounced saddle-shape conformation of the porphyrin cage.
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Affiliation(s)
- Knud Seufert
- Physik Department E20, TU München, James-Franck Strasse, D-85748 Garching, Germany
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39
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Marschall M, Reichert J, Seufert K, Auwärter W, Klappenberger F, Weber-Bargioni A, Klyatskaya S, Zoppellaro G, Nefedov A, Strunskus T, Wöll C, Ruben M, Barth JV. Supramolecular Organization and Chiral Resolution of p-Terphenyl-m-Dicarbonitrile on the Ag(111) Surface. Chemphyschem 2010; 11:1446-51. [DOI: 10.1002/cphc.200900938] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Reichert J, Schiffrin A, Auwärter W, Weber-Bargioni A, Marschall M, Dell'angela M, Cvetko D, Bavdek G, Cossaro A, Morgante A, Barth JV. L-tyrosine on Ag(111): universality of the amino acid 2D zwitterionic bonding scheme? ACS Nano 2010; 4:1218-26. [PMID: 20092357 DOI: 10.1021/nn901669p] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present a combined study of the adsorption and ordering of the l-tyrosine amino acid on the close-packed Ag(111) noble-metal surface in ultrahigh vacuum by means of low-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. On this substrate the biomolecules self-assemble at temperatures exceeding 320 K into linear structures primarily following specific crystallographic directions and evolve with larger molecular coverage into two-dimensional nanoribbons which are commensurate with the underlying atomic lattice. Our high resolution topographical STM data reveal noncovalent molecular dimerization within the highly ordered one-dimensional nanostructures, which recalls the geometrical pattern already seen in the l-methionine/Ag(111) system and supports a universal bonding scheme for amino acids on smooth and unreactive metal surfaces. The molecules desorb for temperatures above 350 K, indicating a relatively weak interaction between the molecules and the substrate. XPS measurements reveal a zwitterionic adsorption, whereas NEXAFS experiments show a tilted adsorption configuration of the phenol moiety. This enables the interdigitation between aromatic side chains of adjacent molecules via parallel-displaced pi-pi interactions which, together with the hydrogen-bonding capability of the hydroxyl functionality, presumably mediates the emergence of the self-assembled supramolecular nanoribbons.
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Affiliation(s)
- Joachim Reichert
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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41
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Weber-Bargioni A, Schwartzberg A, Schmidt M, Harteneck B, Ogletree DF, Schuck PJ, Cabrini S. Functional plasmonic antenna scanning probes fabricated by induced-deposition mask lithography. Nanotechnology 2010; 21:065306. [PMID: 20061594 DOI: 10.1088/0957-4484/21/6/065306] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have fabricated plasmonic bowtie antennae on the apex of silicon atomic-force microscope cantilever tips that enhance the local silicon Raman scattering intensity by approximately 4 x 10(4) when excited near the antenna resonance. The antennae were fabricated using a novel method, induced-deposition mask lithography (IDML), capable of creating high-purity metallic nanostructures on non-planar, non-conducting substrates with high repeatability. IDML involves electron-beam-induced deposition of a W or SiO(x) hard mask on the material to be pattered, here a 20 nm Au film, followed by Ar ion etching to remove the mask and the unmasked gold, leaving a chemically pure Au bowtie antenna. Antenna function and reproducibility was confirmed by comparing Raman spectra for excitation polarized parallel and perpendicular to the antenna axis, as well as by dark-field spectroscopic characterization of resonant modes. The field enhancement of these plasmonic AFM antennae tips was comparable with antennae produced by electron-beam lithography on flat substrates.
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Affiliation(s)
- A Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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42
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Zhang Z, Weber-Bargioni A, Wu SW, Dhuey S, Cabrini S, Schuck PJ. Manipulating nanoscale light fields with the asymmetric bowtie nano-colorsorter. Nano Lett 2009; 9:4505-4509. [PMID: 19899744 DOI: 10.1021/nl902850f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present a class of devices called Asymmetric Bowtie nano-Colorsorters. These devices are specifically engineered to not only capture and confine optical fields, but also to spectrally filter and steer them while maintaining nanoscale field distributions. We show that spectral properties and localized spatial mode distributions can be readily tuned by controlled asymmetry. Nano-Colorsorters can control light's spatial and spectral distributions at the nanoscale and thus significantly impact applications ranging from broadband light harvesting to ultrafast wavelength-selective photodetection.
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Affiliation(s)
- Z Zhang
- Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
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43
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Schmidt M, Schwartzberg AM, Perera PN, Weber-Bargioni A, Carroll A, Sarkar P, Bosneaga E, Urban JJ, Song J, Balakshin MY, Capanema EA, Auer M, Adams PD, Chiang VL, Schuck PJ. Label-free in situ imaging of lignification in the cell wall of low lignin transgenic Populus trichocarpa. Planta 2009; 230:589-97. [PMID: 19526248 PMCID: PMC2715566 DOI: 10.1007/s00425-009-0963-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 05/25/2009] [Indexed: 05/19/2023]
Abstract
Chemical imaging by confocal Raman microscopy has been used for the visualization of the cellulose and lignin distribution in wood cell walls. Lignin reduction in wood can be achieved by, for example, transgenic suppression of a monolignol biosynthesis gene encoding 4-coumarate-CoA ligase (4CL). Here, we use confocal Raman microscopy to compare lignification in wild type and lignin-reduced 4CL transgenic Populus trichocarpa stem wood with spatial resolution that is sub-microm. Analyzing the lignin Raman bands in the spectral region between 1,600 and 1,700 cm(-1), differences in lignin signal intensity and localization are mapped in situ. Transgenic reduction of lignin is particularly pronounced in the S2 wall layer of fibers, suggesting that such transgenic approach may help overcome cell wall recalcitrance to wood saccharification. Spatial heterogeneity in the lignin composition, in particular with regard to ethylenic residues, is observed in both samples.
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Affiliation(s)
- M. Schmidt
- Energy Biosciences Institute, University of California, Berkeley, CA 94720 USA
| | - A. M. Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - P. N. Perera
- Energy Biosciences Institute, University of California, Berkeley, CA 94720 USA
| | - A. Weber-Bargioni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - A. Carroll
- Energy Biosciences Institute, University of California, Berkeley, CA 94720 USA
- Department of Biology, Stanford University, Stanford, CA 94305 USA
| | - P. Sarkar
- Energy Biosciences Institute, University of California, Berkeley, CA 94720 USA
| | - E. Bosneaga
- Energy Biosciences Institute, University of California, Berkeley, CA 94720 USA
| | - J. J. Urban
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - J. Song
- Forest Biotechnology Group, Department of Forestry and Environmental Resources, College of Natural Resources, North Carolina State University, Raleigh, NC 27695 USA
- Institute of Medicinal Plant Development, Peking Union Medical College, Chinese Academy of Medical Sciences, Xibeiwang, Haidian District, 100094 Beijing, People’s Republic of China
| | - M. Y. Balakshin
- Forest Biotechnology Group, Department of Forestry and Environmental Resources, College of Natural Resources, North Carolina State University, Raleigh, NC 27695 USA
| | - E. A. Capanema
- Forest Biotechnology Group, Department of Forestry and Environmental Resources, College of Natural Resources, North Carolina State University, Raleigh, NC 27695 USA
| | - M. Auer
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - P. D. Adams
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - V. L. Chiang
- Forest Biotechnology Group, Department of Forestry and Environmental Resources, College of Natural Resources, North Carolina State University, Raleigh, NC 27695 USA
| | - P. James Schuck
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
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Klappenberger F, Weber-Bargioni A, Auwärter W, Marschall M, Schiffrin A, Barth JV. Temperature dependence of conformation, chemical state, and metal-directed assembly of tetrapyridyl-porphyrin on Cu(111). J Chem Phys 2008; 129:214702. [DOI: 10.1063/1.3021291] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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45
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Eichberger M, Marschall M, Reichert J, Weber-Bargioni A, Auwärter W, Wang RLC, Kreuzer HJ, Pennec Y, Schiffrin A, Barth JV. Dimerization boosts one-dimensional mobility of conformationally adapted porphyrins on a hexagonal surface atomic lattice. Nano Lett 2008; 8:4608-4613. [PMID: 19367979 DOI: 10.1021/nl802995u] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We employed temperature-controlled fast-scanning tunneling microscopy to monitor the diffusion of tetrapyridylporphyrin molecules on the Cu(111) surface. The data reveal unidirectional thermal migration of conformationally adapted monomers in the 300-360 K temperature range. Surprisingly equally oriented molecules spontaneously form dimers that feature a drastically increased one-dimensional diffusivity. The analysis of the bonding and mobility characteristics indicates that this boost is driven by a collective transport mechanism of a metallosupramolecular complex.
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Affiliation(s)
- M Eichberger
- Department of Physics, AMPEL, The University of British Columbia, Vancouver, Canada
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46
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Weber-Bargioni A, Auwärter W, Klappenberger F, Reichert J, Lefrançois S, Strunskus T, Wöll C, Schiffrin A, Pennec Y, Barth JV. Visualizing the Frontier Orbitals of a Conformationally Adapted Metalloporphyrin. Chemphyschem 2008; 9:89-94. [DOI: 10.1002/cphc.200700600] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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47
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Auwärter W, Klappenberger F, Weber-Bargioni A, Schiffrin A, Strunskus T, Wöll C, Pennec Y, Riemann A, Barth JV. Conformational Adaptation and Selective Adatom Capturing of Tetrapyridyl-porphyrin Molecules on a Copper (111) Surface. J Am Chem Soc 2007; 129:11279-85. [PMID: 17705476 DOI: 10.1021/ja071572n] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a combined low-temperature scanning tunneling microscopy and near-edge X-ray adsorption fine structure study on the interaction of tetrapyridyl-porphyrin (TPyP) molecules with a Cu(111) surface. A novel approach using data from complementary experimental techniques and charge density calculations allows us to determine the adsorption geometry of TPyP on Cu(111). The molecules are centered on "bridge" sites of the substrate lattice and exhibit a strong deformation involving a saddle-shaped macrocycle distortion as well as considerable rotation and tilting of the meso-substituents. We propose a bonding mechanism based on the pyridyl-surface interaction, which mediates the molecular deformation upon adsorption. Accordingly, a functionalization by pyridyl groups opens up pathways to control the anchoring of large organic molecules on metal surfaces and tune their conformational state. Furthermore, we demonstrate that the affinity of the terminal groups for metal centers permits the selective capture of individual iron atoms at low temperature.
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Affiliation(s)
- Willi Auwärter
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T1Z4, Canada.
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Auwärter W, Weber-Bargioni A, Brink S, Riemann A, Schiffrin A, Ruben M, Barth JV. Controlled metalation of self-assembled porphyrin nanoarrays in two dimensions. Chemphyschem 2007; 8:250-4. [PMID: 17167810 DOI: 10.1002/cphc.200600675] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report a bottom-up approach for the fabrication of metallo-porphyrin compounds and nanoarchitectures in two dimensions. Scanning tunneling microscopy and tunneling spectroscopy observations elucidate the interaction of highly regular porphyrin layers self-assembled on a Ag(111) surface with iron monomers supplied by an atomic beam. The Fe is shown to be incorporated selectively in the porphyrin macrocycle whereby the template structure is strictly preserved. The immobilization of the molecular reactants allows the identification of single metalation events in a novel reaction scheme. Because the template layers provide extended arrays of reaction sites, superlattices of coordinatively unsaturated and magnetically active metal centers are obtained. This approach offers novel pathways to realize metallo-porphyrin compounds, low-dimensional metal-organic architectures and patterned surfaces which cannot be achieved by conventional means.
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Affiliation(s)
- Willi Auwärter
- Departments of Chemistry and Physics & Astronomy, University of British Columbia, Vancouver, B.C. V6T 1Z4, Canada.
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49
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Pennec Y, Auwärter W, Schiffrin A, Weber-Bargioni A, Riemann A, Barth JV. Supramolecular gratings for tuneable confinement of electrons on metal surfaces. Nat Nanotechnol 2007; 2:99-103. [PMID: 18654227 DOI: 10.1038/nnano.2006.212] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 12/21/2006] [Indexed: 05/26/2023]
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50
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Auwärter W, Weber-Bargioni A, Riemann A, Schiffrin A, Gröning O, Fasel R, Barth JV. Self-assembly and conformation of tetrapyridyl-porphyrin molecules on Ag(111). J Chem Phys 2006; 124:194708. [PMID: 16729835 DOI: 10.1063/1.2194541] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a low-temperature scanning tunneling microscopy (STM) study on the supramolecular ordering of tetrapyridyl-porphyrin (TPyP) molecules on Ag(111). Vapor deposition in a wide substrate temperature range reveals that TPyP molecules easily diffuse and self-assemble into large, highly ordered chiral domains. We identify two mirror-symmetric unit cells, each containing two differently oriented molecules. From an analysis of the respective arrangement it is concluded that lateral intermolecular interactions control the packing of the layer, while its orientation is induced by the coupling to the substrate. This finding is corroborated by molecular mechanics calculations. High-resolution STM images recorded at 15 K allow a direct identification of intramolecular features. This makes it possible to determine the molecular conformation of TPyP on Ag(111). The pyridyl groups are alternately rotated out of the porphyrin plane by an angle of 60 degrees.
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Affiliation(s)
- W Auwärter
- Department of Chemistry and Physics & Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
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