1
|
Geng H, Tang J, Wu Y, Yu Y, Guest JR, Zhang R. Imaging Valley Excitons in a 2D Semiconductor with Scanning Tunneling Microscope-Induced Luminescence. ACS NANO 2024; 18:8961-8970. [PMID: 38470346 DOI: 10.1021/acsnano.3c12555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Valley excitons dominate the optoelectronic response of transition-metal dichalcogenides and are drastically affected by structural and environmental inhomogeneities localized in these materials. Critical to understanding and controlling these nanoscale excitonic changes is the ability to correlate the imaging of excitonic states with crystalline structures on the atomic scale. Here, we apply scanning tunneling microscope-induced luminescence microscopy to image valley excitons in a semiconducting transition-metal dichalcogenide monolayer decoupled by a 10 nanometer-thick hexagonal-boron-nitride flake incorporated in a lateral homojunction on an Au electrode surface. This design enables the observation of chiral excitonic emission arising from neutral and charged valley excitons of the monolayer semiconductor at ambipolar voltages with a quantum efficiency up to ∼10-5 photon/electron. The measured light helicity demonstrates considerable circular polarization dependent on the sample voltage, reaching as much as 40%. The real-space luminescence imaging maps─at subnanometer resolution─of the valley excitons reveal striking spatial variations associated with localized inhomogeneities, including surface impurities and possibly nanoscale dielectric and/or potential disorders in the monolayer. Our study introduces a promising format for 2D materials to explore and tailor their optoelectronic processes at the atomic scale.
Collapse
Affiliation(s)
- Hairui Geng
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Jie Tang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Yanwei Wu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Yuanqin Yu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Jeffrey R Guest
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Rui Zhang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| |
Collapse
|
2
|
Shan S, Huang J, Papadopoulos S, Khelifa R, Taniguchi T, Watanabe K, Wang L, Novotny L. Overbias Photon Emission from Light-Emitting Devices Based on Monolayer Transition Metal Dichalcogenides. NANO LETTERS 2023; 23:10908-10913. [PMID: 38048755 PMCID: PMC10722526 DOI: 10.1021/acs.nanolett.3c03155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 11/24/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023]
Abstract
Tunneling light-emitting devices (LEDs) based on transition metal dichalcogenides (TMDs) and other two-dimensional (2D) materials are a new platform for on-chip optoelectronic integration. Some of the physical processes underlying this LED architecture are not fully understood, especially the emission at photon energies higher than the applied electrostatic potential, so-called overbias emission. Here we report overbias emission for potentials that are near half of the optical bandgap energy in TMD-based tunneling LEDs. We show that this emission is not thermal in nature but consistent with exciton generation via a two-electron coherent tunneling process.
Collapse
Affiliation(s)
- Shengyu Shan
- Photonics
Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | - Jing Huang
- Photonics
Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | | | - Ronja Khelifa
- Photonics
Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Lujun Wang
- Photonics
Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | - Lukas Novotny
- Photonics
Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| |
Collapse
|
3
|
Wang L, Papadopoulos S, Iyikanat F, Zhang J, Huang J, Taniguchi T, Watanabe K, Calame M, Perrin ML, García de Abajo FJ, Novotny L. Exciton-assisted electron tunnelling in van der Waals heterostructures. NATURE MATERIALS 2023; 22:1094-1099. [PMID: 37365227 PMCID: PMC10465355 DOI: 10.1038/s41563-023-01556-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 04/17/2023] [Indexed: 06/28/2023]
Abstract
The control of elastic and inelastic electron tunnelling relies on materials with well-defined interfaces. Two-dimensional van der Waals materials are an excellent platform for such studies. Signatures of acoustic phonons and defect states have been observed in current-to-voltage measurements. These features can be explained by direct electron-phonon or electron-defect interactions. Here we use a tunnelling process that involves excitons in transition metal dichalcogenides (TMDs). We study tunnel junctions consisting of graphene and gold electrodes separated by hexagonal boron nitride with an adjacent TMD monolayer and observe prominent resonant features in current-to-voltage measurements appearing at bias voltages that correspond to TMD exciton energies. By placing the TMD outside of the tunnelling pathway, we demonstrate that this tunnelling process does not require any charge injection into the TMD. The appearance of such optical modes in electrical transport introduces additional functionality towards van der Waals material-based optoelectronic devices.
Collapse
Affiliation(s)
- Lujun Wang
- Photonics Laboratory, ETH Zürich, Zürich, Switzerland
| | | | - Fadil Iyikanat
- Institut de Ciències Fotòniques (ICFO), The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Jian Zhang
- Transport at Nanoscale Interfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Jing Huang
- Photonics Laboratory, ETH Zürich, Zürich, Switzerland
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Michel Calame
- Transport at Nanoscale Interfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Department of Physics, University of Basel, Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
| | - Mickael L Perrin
- Transport at Nanoscale Interfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich, Switzerland
- Quantum Center, ETH Zürich, Zürich, Switzerland
| | - F Javier García de Abajo
- Institut de Ciències Fotòniques (ICFO), The Barcelona Institute of Science and Technology, Castelldefels, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
| | - Lukas Novotny
- Photonics Laboratory, ETH Zürich, Zürich, Switzerland.
| |
Collapse
|
4
|
Yu YJ, Kuai Y, Fan YT, Zhu LF, Kong FF, Tian XJ, Jing SH, Zhang L, Zhang DG, Zhang Y, Zhang Y, Dong ZC. Back focal plane imaging for light emission from a tunneling junction in a low-temperature ultrahigh-vacuum scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:063703. [PMID: 37862523 DOI: 10.1063/5.0147401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/04/2023] [Indexed: 10/22/2023]
Abstract
We report the design and realization of the back focal plane (BFP) imaging for the light emission from a tunnel junction in a low-temperature ultrahigh-vacuum (UHV) scanning tunneling microscope (STM). To achieve the BFP imaging in a UHV environment, a compact "all-in-one" sample holder is designed and fabricated, which allows us to integrate the sample substrate with the photon collection units that include a hemisphere solid immersion lens and an aspherical collecting lens. Such a specially designed holder enables the characterization of light emission both within and beyond the critical angle and also facilitates the optical alignment inside a UHV chamber. To test the performance of the BFP imaging system, we first measure the photoluminescence from dye-doped polystyrene beads on a thin Ag film. A double-ring pattern is observed in the BFP image, arising from two kinds of emission channels: strong surface plasmon coupled emissions around the surface plasmon resonance angle and weak transmitted fluorescence maximized at the critical angle, respectively. Such an observation also helps to determine the emission angle for each image pixel in the BFP image and, more importantly, proves the feasibility of our BFP imaging system. Furthermore, as a proof-of-principle experiment, electrically driven plasmon emissions are used to demonstrate the capability of the constructed BFP imaging system for STM induced electroluminescence measurements. A single-ring pattern is obtained in the BFP image, which reveals the generation and detection of the leakage radiation from the surface plasmon propagating on the Ag surface. Further analyses of the BFP image provide valuable information on the emission angle of the leakage radiation, the orientation of the radiating dipole, and the plasmon wavevector. The UHV-BFP imaging technique demonstrated here opens new routes for future studies on the angular distributed emission and dipole orientation of individual quantum emitters in UHV.
Collapse
Affiliation(s)
- Yun-Jie Yu
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Yan Kuai
- Advanced Laser Technology Laboratory of Anhui Province, Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yong-Tao Fan
- Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Liang-Fu Zhu
- Advanced Laser Technology Laboratory of Anhui Province, Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Fan-Fang Kong
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiao-Jun Tian
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shi-Hao Jing
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Li Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Dou-Guo Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
- Advanced Laser Technology Laboratory of Anhui Province, Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yao Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yang Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhen-Chao Dong
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| |
Collapse
|
5
|
Alves E, Péchou R, Coratger R, Mlayah A. Gap plasmon modes and plasmon-exciton coupling in a hybrid Au/MoSe 2/Au tunneling junction. OPTICS EXPRESS 2023; 31:12549-12561. [PMID: 37157412 DOI: 10.1364/oe.479620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The light-matter interaction between plasmonic nanocavity modes and excitons at the nanometer scale is here addressed in the scanning tunneling microscope configuration where an MoSe2 monolayer is located between the tip and the substrate. We investigate by optical excitation the electromagnetic modes of this hybrid Au/MoSe2/Au tunneling junction using numerical simulations where electron tunneling and the anisotropic character of the MoSe2 layer are taken into account. In particular, we pointed out gap plasmon modes and Fano-type plasmon-exciton coupling taking place at the MoSe2/Au substrate interface. The spectral properties and spatial localization of these modes are studied as a function of the tunneling parameters and incident polarization.
Collapse
|
6
|
López LEP, Rosławska A, Scheurer F, Berciaud S, Schull G. Tip-induced excitonic luminescence nanoscopy of an atomically resolved van der Waals heterostructure. NATURE MATERIALS 2023; 22:482-488. [PMID: 36928383 DOI: 10.1038/s41563-023-01494-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
The electronic and optical properties of van der Waals heterostructures are strongly influenced by the structuration and homogeneity of their nano- and atomic-scale environments. Unravelling this intimate structure-property relationship is a key challenge that requires methods capable of addressing the light-matter interactions in van der Waals materials with ultimate spatial resolution. Here we use a low-temperature scanning tunnelling microscope to probe-with atomic-scale resolution-the excitonic luminescence of a van der Waals heterostructure, made of a transition metal dichalcogenide monolayer stacked onto a few-layer graphene flake supported by a Au(111) substrate. Sharp emission lines arising from neutral, charged and localized excitons are reported. Their intensities and emission energies vary as a function of the nanoscale topography of the van der Waals heterostructure, explaining the variability of the emission properties observed with diffraction-limited approaches. Our work paves the way towards understanding and controlling optoelectronic phenomena in moiré superlattices with atomic-scale resolution.
Collapse
Affiliation(s)
- Luis E Parra López
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France
| | - Anna Rosławska
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France
| | - Fabrice Scheurer
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France.
| | - Guillaume Schull
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France.
| |
Collapse
|
7
|
Xiao J, Zhao W, Li L, Ma L, Tian G. Adsorption properties of a paracyclophane molecule on NaCl/Au surfaces: a first-principles study. Phys Chem Chem Phys 2023; 25:6060-6066. [PMID: 36751852 DOI: 10.1039/d2cp04745d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ultrathin insulating layers are commonly applied in scanning tunneling microscope (STM) measurements on molecular systems to preserve the intrinsic properties of a sample. We examine in the present work the adsorption properties of a double-decker 3,3-paracyclophane (PCP) molecule supported on Au surfaces with thin NaCl monolayers (MLs) as the decoupling spacer by using first-principles calculations. The interactions between the adsorbed molecule and the substrate were analyzed in terms of the adsorption energy, dispersion interactions, charge transfer, and molecular structure changes. The simulation results show that the presence of NaCl can significantly reduce the adsorption energy as well as the charge transfer between the molecule and the substrate. Detailed analysis of the differential charge density and partial charge density of states indicates that three MLs of NaCl are sufficient to decouple the molecule from the Au substrate with no significant changes in the adsorption properties of the PCP with the further increase of the thickness of the NaCl spacer. These results could be helpful for the application of the interesting double-decker molecules as functional single-molecule devices where the intrinsic molecular properties need to be preserved.
Collapse
Affiliation(s)
- Jiyin Xiao
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Wenjing Zhao
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Li Li
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Liang Ma
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Guangjun Tian
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| |
Collapse
|
8
|
Peña Román RJ, Bretel R, Pommier D, Parra López LE, Lorchat E, Boer-Duchemin E, Dujardin G, Borisov AG, Zagonel LF, Schull G, Berciaud S, Le Moal E. Tip-Induced and Electrical Control of the Photoluminescence Yield of Monolayer WS 2. NANO LETTERS 2022; 22:9244-9251. [PMID: 36458911 DOI: 10.1021/acs.nanolett.2c02142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The photoluminescence (PL) of monolayer tungsten disulfide (WS2) is locally and electrically controlled using the nonplasmonic tip and tunneling current of a scanning tunneling microscope (STM). The spatial and spectral distribution of the emitted light is determined using an optical microscope. When the STM tip is engaged, short-range PL quenching due to near-field electromagnetic effects is present, independent of the sign and value of the bias voltage applied to the tip-sample tunneling junction. In addition, a bias-voltage-dependent long-range PL quenching is measured when the sample is positively biased. We explain these observations by considering the native n-doping of monolayer WS2 and the charge carrier density gradients induced by electron tunneling in micrometer-scale areas around the tip position. The combination of wide-field PL microscopy and charge carrier injection using an STM opens up new ways to explore the interplay between excitons and charge carriers in two-dimensional semiconductors.
Collapse
Affiliation(s)
- Ricardo Javier Peña Román
- Institute of Physics "Gleb Wataghin", Department of Applied Physics, State University of Campinas-UNICAMP, 13083-859 Campinas, Brazil
| | - Rémi Bretel
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Delphine Pommier
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Luis Enrique Parra López
- Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Etienne Lorchat
- Physics & Informatics (PHI) Laboratories, NTT Research, Inc., Sunnyvale, California 94085, United States
| | - Elizabeth Boer-Duchemin
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Gérald Dujardin
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Andrei G Borisov
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Luiz Fernando Zagonel
- Institute of Physics "Gleb Wataghin", Department of Applied Physics, State University of Campinas-UNICAMP, 13083-859 Campinas, Brazil
| | - Guillaume Schull
- Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Stéphane Berciaud
- Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Eric Le Moal
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| |
Collapse
|
9
|
Ma Y, Kalt RA, Stemmer A. Local strain and tunneling current modulate excitonic luminescence in MoS 2 monolayers. RSC Adv 2022; 12:24922-24929. [PMID: 36199876 PMCID: PMC9434384 DOI: 10.1039/d2ra05123k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 08/26/2022] [Indexed: 11/21/2022] Open
Abstract
The excitonic luminescence of monolayer molybdenum disulfide (MoS2) on a gold substrate is studied by scanning tunneling microscopy (STM). STM-induced light emission (STM-LE) from MoS2 is assigned to the radiative decay of A and B excitons. The intensity ratio of A and B exciton emission is modulated by the tunneling current, since the A exciton emission intensity saturates at high tunneling currents. Moreover, the corrugated gold substrate introduces local strain to the monolayer MoS2, resulting in significant changes of electronic bandgap and valence band splitting. The modulation rate of strain on A exciton energy is estimated as -69 ± 5 meV/%. STM-LE provides a direct link between exciton energy and local strain in monolayer MoS2 on a length scale of 10 nm.
Collapse
Affiliation(s)
- Yalan Ma
- Nanotechnology Group, ETH Zürich Säumerstrasse 4 Rüschlikon 8803 Switzerland
| | - Romana Alice Kalt
- Nanotechnology Group, ETH Zürich Säumerstrasse 4 Rüschlikon 8803 Switzerland
| | - Andreas Stemmer
- Nanotechnology Group, ETH Zürich Säumerstrasse 4 Rüschlikon 8803 Switzerland
| |
Collapse
|
10
|
Karni O, Esin I, Dani KM. Through the Lens of a Momentum Microscope: Viewing Light-Induced Quantum Phenomena in 2D Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2204120. [PMID: 35817468 DOI: 10.1002/adma.202204120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Van der Waals (vdW) materials at their 2D limit are diverse, flexible, and unique laboratories to study fundamental quantum phenomena and their future applications. Their novel properties rely on their pronounced Coulomb interactions, variety of crystal symmetries and spin-physics, and the ease of incorporation of different vdW materials to form sophisticated heterostructures. In particular, the excited state properties of many 2D semiconductors and semi-metals are relevant for their technological applications, particularly those that can be induced by light. In this paper, the recent advances made in studying out-of-equilibrium, light-induced, phenomena in these materials are reviewed using powerful, surface-sensitive, time-resolved photoemission-based techniques, with a particular emphasis on the emerging multi-dimensional photoemission spectroscopy technique of time-resolved momentum microscopy. The advances this technique has enabled in studying the nature and dynamics of occupied excited states in these materials are discussed. Then, the future research directions opened by these scientific and instrumental advancements are projected for studying the physics of 2D materials and the opportunities to engineer their band-structure and band-topology by laser fields.
Collapse
Affiliation(s)
- Ouri Karni
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Iliya Esin
- Department of Physics, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Keshav M Dani
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, 904-0495, Japan
| |
Collapse
|
11
|
Peña Román RJ, Auad Y, Grasso L, Padilha LA, Alvarez F, Barcelos ID, Kociak M, Zagonel LF. Design and implementation of a device based on an off-axis parabolic mirror to perform luminescence experiments in a scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:043704. [PMID: 35489916 DOI: 10.1063/5.0078423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
We present the design, implementation, and illustrative results of a light collection/injection strategy based on an off-axis parabolic mirror collector for a low-temperature Scanning Tunneling Microscope (STM). This device allows us to perform STM induced Light Emission (STM-LE) and Cathodoluminescence (STM-CL) experiments and in situ Photoluminescence (PL) and Raman spectroscopy as complementary techniques. Considering the Étendue conservation and using an off-axis parabolic mirror, it is possible to design a light collection and injection system that displays 72% of collection efficiency (considering the hemisphere above the sample surface) while maintaining high spectral resolution and minimizing signal loss. The performance of the STM is tested by atomically resolved images and scanning tunneling spectroscopy results on standard sample surfaces. The capabilities of our system are demonstrated by performing STM-LE on metallic surfaces and two-dimensional semiconducting samples, observing both plasmonic and excitonic emissions. In addition, we carried out in situ PL measurements on semiconducting monolayers and quantum dots and in situ Raman on graphite and hexagonal boron nitride (h-BN) samples. Additionally, STM-CL and PL were obtained on monolayer h-BN gathering luminescence spectra that are typically associated with intragap states related to carbon defects. The results show that the flexible and efficient light injection and collection device based on an off-axis parabolic mirror is a powerful tool to study several types of nanostructures with multiple spectroscopic techniques in correlation with their morphology at the atomic scale and electronic structure.
Collapse
Affiliation(s)
- Ricardo Javier Peña Román
- "Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Yves Auad
- "Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Lucas Grasso
- "Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Lazaro A Padilha
- "Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Fernando Alvarez
- "Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| | - Ingrid David Barcelos
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970 Campinas, SP, Brazil
| | - Mathieu Kociak
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay, France
| | - Luiz Fernando Zagonel
- "Gleb Wataghin" Institute of Physics, University of Campinas-UNICAMP, 13083-859 Campinas, SP, Brazil
| |
Collapse
|
12
|
Brinker S, Küster F, Parkin SSP, Sessi P, Lounis S. Anomalous excitations of atomically crafted quantum magnets. SCIENCE ADVANCES 2022; 8:eabi7291. [PMID: 35080983 PMCID: PMC8791613 DOI: 10.1126/sciadv.abi7291] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
High-energy resolution spectroscopic studies of quantum magnets proved extremely valuable in accessing magnetodynamics quantities, such as energy barriers, magnetic interactions, and lifetime of excited states. Here, we investigate a previously unexplored flavor of low-energy spin excitations for quantum spins coupled to an electron bath. In sharp contrast to the usual tunneling signature of two steps symmetrically centered around the Fermi level, we find a single step in the conductance. Combining time-dependent and many-body perturbation theories, magnetic field-dependent tunneling spectra are explained as the result of an interplay between weak magnetic anisotropy energy, magnetic interactions, and Stoner-like electron-hole excitations that are strongly dependent on the magnetic states of the nanostructures. The results are rationalized in terms of a noncollinear magnetic ground state and the dominance of ferro- and antiferromagnetic interactions. The atomically crafted nanomagnets offer an appealing model for the exploration of electrically pumped spin systems.
Collapse
Affiliation(s)
- Sascha Brinker
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich D-52425, Germany
| | - Felix Küster
- Max Planck Institute of Microstructure Physics, Halle 06120, Germany
| | | | - Paolo Sessi
- Max Planck Institute of Microstructure Physics, Halle 06120, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich D-52425, Germany
- Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany
| |
Collapse
|
13
|
Doležal J, Canola S, Hapala P, de Campos Ferreira RC, Merino P, Švec M. Real Space Visualization of Entangled Excitonic States in Charged Molecular Assemblies. ACS NANO 2022; 16:1082-1088. [PMID: 34919384 DOI: 10.1021/acsnano.1c08816] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Entanglement of excitons holds great promise for the future of quantum computing, which would use individual molecular dyes as building blocks of their circuitry. Studying entangled excitonic eigenstates emerging in coupled molecular assemblies in the near-field with submolecular resolution has the potential to bring insight into the photophysics of these fascinating quantum phenomena. In contrast to far-field spectroscopies, near-field spectroscopic mapping permits direct identification of the individual eigenmodes, type of exciton coupling, including excited states otherwise inaccessible in the far field (dark states). Here we combine tip-enhanced spectromicroscopy with atomic force microscopy to inspect delocalized single-exciton states of charged molecular assemblies engineered from individual perylenetetracarboxylic dianhydride (PTCDA) molecules. Hyperspectral mapping of the eigenstates and comparison with calculated many-body optical transitions reveals a second low-lying excited state of the anion monomers and its role in the exciton entanglement within the assemblies. We demonstrate control over the exciton coupling by switching the assembly charge states. Our results reveal the possibility of tailoring excitonic properties of organic dye aggregates for advanced functionalities and establish the methodology to address them individually at the nanoscale.
Collapse
Affiliation(s)
- Jiří Doležal
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, Praha 2 CZ12116, Czech Republic
| | - Sofia Canola
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
| | - Prokop Hapala
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
| | | | - Pablo Merino
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, E28049 Madrid, Spain
- Instituto de Física Fundamental, CSIC, Serrano 121, E28006 Madrid, Spain
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10/112, Praha 6 CZ16200, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Šlechtitelů 27, CZ78371 Olomouc, Czech Republic
| |
Collapse
|
14
|
Bonnet N, Lee HY, Shao F, Woo SY, Blazit JD, Watanabe K, Taniguchi T, Zobelli A, Stéphan O, Kociak M, Gradečak S, Tizei LHG. Nanoscale Modification of WS 2 Trion Emission by Its Local Electromagnetic Environment. NANO LETTERS 2021; 21:10178-10185. [PMID: 34878799 DOI: 10.1021/acs.nanolett.1c02600] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Structural, electronic, and chemical nanoscale modifications of transition metal dichalcogenide monolayers alter their optical properties. A key missing element for complete control is a direct spatial correlation of optical response to nanoscale modifications due to the large gap in spatial resolution between optical spectroscopy and nanometer-resolved techniques. Here, we bridge this gap by obtaining nanometer-resolved optical properties using electron spectroscopy at cryogenic temperatures, specifically electron energy loss spectroscopy for absorption and cathodoluminescence for emission, which are then directly correlated to chemical and structural information. In an h-BN/WS2/h-BN heterostructure, we observe local modulation of the trion (X-) emission due to tens of nanometer wide dielectric patches. Trion emission also increases in regions where charge accumulation occurs, close to the carbon film supporting the heterostructures. The localized exciton emission (L) detected here is not correlated to strain above 1%, suggesting point defects might be involved in their formation.
Collapse
Affiliation(s)
- Noémie Bonnet
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Hae Yeon Lee
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02141, United States
| | - Fuhui Shao
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Steffi Y Woo
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Jean-Denis Blazit
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - 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
| | - Alberto Zobelli
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Odile Stéphan
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Mathieu Kociak
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Silvija Gradečak
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02141, United States
| | - Luiz H G Tizei
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay, France
| |
Collapse
|
15
|
Zhang W, Enriquez H, Tong Y, Mayne AJ, Bendounan A, Smogunov A, Dappe YJ, Kara A, Dujardin G, Oughaddou H. Flat epitaxial quasi-1D phosphorene chains. Nat Commun 2021; 12:5160. [PMID: 34453043 PMCID: PMC8397792 DOI: 10.1038/s41467-021-25262-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 07/21/2021] [Indexed: 02/07/2023] Open
Abstract
The emergence of peculiar phenomena in 1D phosphorene chains (P chains) has been proposed in theoretical studies, notably the Stark and Seebeck effects, room temperature magnetism, and topological phase transitions. Attempts so far to fabricate P chains, using the top-down approach starting from a few layers of bulk black phosphorus, have failed to produce reliably precise control of P chains. We show that molecular beam epitaxy gives a controllable bottom-up approach to grow atomically thin, crystalline 1D flat P chains on a Ag(111) substrate. Scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and density functional theory calculations reveal that the armchair-shaped chains are semiconducting with an intrinsic 1.80 ± 0.20 eV band gap. This could make these P chains an ideal material for opto-electronic devices.
Collapse
Affiliation(s)
- Wei Zhang
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, Orsay, France
| | - Hanna Enriquez
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, Orsay, France
| | - Yongfeng Tong
- TEMPO Beamline, Synchrotron SOLEIL, Gif-sur-Yvette, Cedex, France
| | - Andrew J Mayne
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, Orsay, France
| | | | - Alex Smogunov
- Université Paris-Saclay, CNRS, CEA, Service de Physique de l'Etat Condensé, Gif-sur-Yvette, France
| | - Yannick J Dappe
- Université Paris-Saclay, CNRS, CEA, Service de Physique de l'Etat Condensé, Gif-sur-Yvette, France
| | - Abdelkader Kara
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Gérald Dujardin
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, Orsay, France
| | - Hamid Oughaddou
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, Orsay, France.
- Département de Physique, CY Cergy Paris Université, Cergy-Pontoise, Cedex, France.
| |
Collapse
|
16
|
Danz N, Occhicone A, Pflumm C, Munzert P, Michelotti F, Michaelis D. Spectral analysis of organic LED emitters' orientation in thin layers by resonant emission on dielectric stacks. OPTICS EXPRESS 2021; 29:6608-6619. [PMID: 33726178 DOI: 10.1364/oe.417531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
Purposely tailored thin film stacks sustaining surface waves have been utilized to create a unique link between emission angle and wavelength of fluorescent dye molecules. The knowledge of the thin film stack's properties allows us to derive the intrinsically emitted luminescence spectrum as well as to gain information about the orientation of fluorophores from angularly resolved experiments. This corresponds to replacing all the equipment necessary for polarized spectroscopy with a single smart thin film stack, potentially enabling single shot analyses in the future. The experimental results agree well with those from other established techniques, when analyzing the Rubrene derivative in a 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T) host used for the fabrication of optimized organic light-emitting diodes. The findings illustrate how resonant layered stacks can be applied to integrated spectroscopic analyses.
Collapse
|
17
|
Chen Y, Huang L, Chen H, Chen Z, Zhang H, Xiao Z, Hong W. Towards Responsive
Single‐Molecule
Device. CHINESE J CHEM 2021. [DOI: 10.1002/cjoc.202000420] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Yaorong Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Longfeng Huang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Hang Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Zhixin Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Hewei Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Zongyuan Xiao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University Xiamen Fujian 361005 China
| |
Collapse
|
18
|
Lebedev DV, Shkoldin VA, Mozharov AM, Permyakov DV, Dvoretckaia LN, Bogdanov AA, Samusev AK, Golubok AO, Mukhin IS. Scanning Tunneling Microscopy-Induced Light Emission and I( V) Study of Optical Near-Field Properties of Single Plasmonic Nanoantennas. J Phys Chem Lett 2021; 12:501-507. [PMID: 33373245 DOI: 10.1021/acs.jpclett.0c03039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Electrically driven plasmonic nanoantennas can be integrated as a local source of the optical signal of advanced photonic schemes for on-chip data processing. The inelastic electron tunneling provides the photon generation or launch of surface plasmon waves. This process can be enhanced by the local density of optical states of nanoantennas. In this paper, we used scanning tunnel microscopy-induced light emission to probe the local optoelectronic properties of single gold nanodiscs. The electromagnetic field distribution in the vicinity of plasmonic structures was investigated with high spatial resolution. The obtained photon maps reveal the nonuniform distribution of electromagnetic near-fields, which is consistent with nanoantenna optical modes. Also, the analysis of derived I(V) curves showed a direct correlation between the nanoantenna optical states and the appearance of features on current-voltage characteristics.
Collapse
Affiliation(s)
- Denis V Lebedev
- Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
- Institute for Analytical Instrumentation RAS, 26 Rizhskii pr., St. Petersburg 190103, Russia
- St. Petersburg Academic University, 8/3 Khlopina str., St. Petersburg 194021, Russia
| | - Vitaliy A Shkoldin
- St. Petersburg Academic University, 8/3 Khlopina str., St. Petersburg 194021, Russia
- ITMO University, 9 Kronverksky pr., St. Petersburg 197101, Russia
| | - Alexey M Mozharov
- St. Petersburg Academic University, 8/3 Khlopina str., St. Petersburg 194021, Russia
| | | | - Lilia N Dvoretckaia
- St. Petersburg Academic University, 8/3 Khlopina str., St. Petersburg 194021, Russia
| | | | - Anton K Samusev
- ITMO University, 9 Kronverksky pr., St. Petersburg 197101, Russia
| | - Alexander O Golubok
- Institute for Analytical Instrumentation RAS, 26 Rizhskii pr., St. Petersburg 190103, Russia
| | - Ivan S Mukhin
- St. Petersburg Academic University, 8/3 Khlopina str., St. Petersburg 194021, Russia
- ITMO University, 9 Kronverksky pr., St. Petersburg 197101, Russia
| |
Collapse
|
19
|
A new view on the origin of zero-bias anomalies of Co atoms atop noble metal surfaces. Nat Commun 2020; 11:6112. [PMID: 33257648 PMCID: PMC7705691 DOI: 10.1038/s41467-020-19746-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 10/21/2020] [Indexed: 11/08/2022] Open
Abstract
Many-body phenomena are paramount in physics. In condensed matter, their hallmark is considerable on a wide range of material characteristics spanning electronic, magnetic, thermodynamic and transport properties. They potentially imprint non-trivial signatures in spectroscopic measurements, such as those assigned to Kondo, excitonic and polaronic features, whose emergence depends on the involved degrees of freedom. Here, we address systematically zero-bias anomalies detected by scanning tunneling spectroscopy on Co atoms deposited on Cu, Ag and Au(111) substrates, which remarkably are almost identical to those obtained from first-principles. These features originate from gaped spin-excitations induced by a finite magnetic anisotropy energy, in contrast to the usual widespread interpretation relating them to Kondo resonances. Resting on relativistic time-dependent density functional and many-body perturbation theories, we furthermore unveil a new many-body feature, the spinaron, resulting from the interaction of electrons and spin-excitations localizing electronic states in a well defined energy.
Collapse
|
20
|
Kim J, Hou S, Zhao H, Forrest SR. Nanoscale Mapping of Morphology of Organic Thin Films. NANO LETTERS 2020; 20:8290-8297. [PMID: 33135904 DOI: 10.1021/acs.nanolett.0c03440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We determine precise nanoscale information about the morphologies of several organic thin film structures using Fourier plane imaging microscopy (FIM). We used FIM microscopy to detect the orientation of molecular transition dipole moments from an extremely low density of luminescent dye molecules, which we call "morphology sensors". The orientation of the sensor molecules is driven by the local film structure and thus can be used to determine details of the host morphology without influencing it. We use symmetric planar phosphorescent dye molecules as the sensors that are deposited into the bulk of organic film hosts during the growth. We demonstrate morphological mapping with a depth resolution to a few Ångstroms that is limited by the ability to determine thickness during deposition, along with an in-plane resolution limited by optical diffraction. Furthermore, we monitor morphological changes arising from thermal annealing of metastable organic films that are commonly employed in photonic devices.
Collapse
Affiliation(s)
- Jongchan Kim
- Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Shaocong Hou
- Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Haonan Zhao
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Stephen R Forrest
- Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Materials Science & Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
21
|
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. SCIENCE ADVANCES 2020; 6:eabb5988. [PMID: 32938664 PMCID: PMC7494346 DOI: 10.1126/sciadv.abb5988] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [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.
Collapse
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
| | | |
Collapse
|
22
|
Peña Román RJ, Auad Y, Grasso L, Alvarez F, Barcelos ID, Zagonel LF. Tunneling-current-induced local excitonic luminescence in p-doped WSe 2 monolayers. NANOSCALE 2020; 12:13460-13470. [PMID: 32614018 DOI: 10.1039/d0nr03400b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We have studied the excitonic properties of exfoliated tungsten diselenide (WSe2) monolayers transferred to gold substrates using the tunneling current in a Scanning Tunneling Microscope (STM) operated in air to excite the light emission locally. In obtained spectra, emission energies are independent of the applied bias voltage and resemble photoluminescence (PL) results, indicating that, in both cases, the light emission is due to neutral and charged exciton recombination. Interestingly, the electron injection rate, that is, the tunneling current, can be used to control the ratio of charged to neutral exciton emission. The obtained quantum yield in the transition metal dichalcogenide (TMD) is ∼5 × 10-7 photons per electron. The proposed excitation mechanism is the direct injection of carriers into the conduction band. The monolayer WSe2 presents bright and dark defects spotted by STM images performed under UHV. STS confirms the sample as p-doped, possibly as a net result of the observed defects. The presence of an interfacial water layer decouples the monolayer from the gold support and allows excitonic emission from the WSe2 monolayer. The creation of a water layer is an inherent feature of the sample transferring process due to the ubiquitous air moisture. Consequently, vacuum thermal annealing, which removes the water layer, quenches excitonic luminescence from the TMD. The tunneling current can locally displace water molecules leading to excitonic emission quenching and to plasmonic emission due to the gold substrate. The present findings extend the use and the understanding of STM induced light emission (STM-LE) on semiconducting TMDs to probe exciton emission and dynamics with high spatial resolution.
Collapse
Affiliation(s)
- Ricardo Javier Peña Román
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Yves Auad
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Lucas Grasso
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Fernando Alvarez
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| | - Ingrid David Barcelos
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970, Campinas, SP, Brazil
| | - Luiz Fernando Zagonel
- Applied Physics Department, "Gleb Wataghin" Institute of Physics, University of Campinas - UNICAMP, 13083-859, Campinas, SP, Brazil.
| |
Collapse
|
23
|
Rosławska A, Leon CC, Grewal A, Merino P, Kuhnke K, Kern K. Atomic-Scale Dynamics Probed by Photon Correlations. ACS NANO 2020; 14:6366-6375. [PMID: 32479059 PMCID: PMC7315641 DOI: 10.1021/acsnano.0c03704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Light absorption and emission have their origins in fast atomic-scale phenomena. To characterize these basic steps (e.g., in photosynthesis, luminescence, and quantum optics), it is necessary to access picosecond temporal and picometer spatial scales simultaneously. In this Perspective, we describe how state-of-the-art picosecond photon correlation spectroscopy combined with luminescence induced at the atomic scale with a scanning tunneling microscope (STM) enables such studies. We outline recent STM-induced luminescence work on single-photon emitters and the dynamics of excitons, charges, molecules, and atoms as well as several prospective experiments concerning light-matter interactions at the nanoscale. We also describe future strategies for measuring and rationalizing ultrafast phenomena at the nanoscale.
Collapse
Affiliation(s)
- Anna Rosławska
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Christopher C. Leon
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Abhishek Grewal
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Pablo Merino
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
- Instituto
de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Inés de la Cruz 3, E28049 Madrid, Spain
- Instituto
de Física Fundamental, CSIC, Serrano 121, E28006 Madrid, Spain
| | - Klaus Kuhnke
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
- Institut
de Physique, École Polytechnique
Fédérale de Lausanne, 1015 Lausanne, Switzerland
| |
Collapse
|