1
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Qin JX, Shen CL, Li L, Liu H, Zhang WY, Yang XG, Shan CX. Broadband Negative Photoconductive Response in Carbon Nanodots. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2404694. [PMID: 38857532 DOI: 10.1002/adma.202404694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/13/2024] [Indexed: 06/12/2024]
Abstract
Due to the broadband response and low selectivity of external light, negative photoconductivity (NPC) effect holds great potential applications in photoelectric devices. Herein, different photoresponsive carbon nanodots (CDs) are prepared from diverse precursors and the broadband response from the NPC CDs are utilized to achieve the optoelectronic logic gates and optical imaging for the first time. In detail, the mcu-CDs which are prepared by the microwave-assisted polymerization of citric acid and urea possess the large specific surface area and abundant hydrophilic groups as sites for the adsorption of H2O molecules and thereby present a high conductivity in dark. Meanwhile, the low affinity of mcu-CDs to H2O molecules permits the light-induced desorption of H2O molecules by heat effect and thus endow the mcu-CDs with a low conductivity under illumination. The easy absorption and desorption of H2O molecules contribute to the extraordinary NPC of mcu-CDs. With the broadband NPC response in CDs, the optoelectronic logic gates and flexible optical imaging system are established, achieving the applications of "NOR" or "NAND" logic operations and high-quality optical images. These findings unveil the unique optoelectronic properties of CDs, and have the potential to advance the applications of CDs in optoelectronic devices.
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Affiliation(s)
- Jin-Xu Qin
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
| | - Cheng-Long Shen
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
| | - Lei Li
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
| | - Hang Liu
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
| | - Wu-You Zhang
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
| | - Xi-Gui Yang
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
- Institute of Quantum Materials and Physics, Henan Academy of Sciences, Zhengzhou, 450046, China
| | - Chong-Xin Shan
- Henan Key Laboratory of Diamond Optoelectronic Material and Devices, Key Laboratory of Material physics, Ministry of Education, School of Physics and Laboratory of Zhongyuan Light, Zhengzhou University, Zhengzhou, 450052, China
- Institute of Quantum Materials and Physics, Henan Academy of Sciences, Zhengzhou, 450046, China
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2
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Li X, Fang Z, Guo X, Wang R, Zhao Y, Zhu W, Wang L, Zhang L. Light-Induced Conductance Potentiation and Depression in an All-Optically Controlled Memristor. ACS APPLIED MATERIALS & INTERFACES 2024; 16:27866-27874. [PMID: 38747412 DOI: 10.1021/acsami.4c02092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Optoelectronic memristors are new multifunctional devices with both electrically tunable and light-tunable synaptic plasticity, attracting great attention as key promising devices for optoelectronic neuromorphic computing systems. At present, the conductance modulation in most optoelectronic memristors is conducted in a hybrid photoelectric mode, suffering some problems such as heat generation and control complexity. Here, an optoelectronic memristor based on the p+-Si/n-ZnO heterojunction is proposed where the conductance can be reversibly modulated in an all-optically controlled mode. The electron detrapping/trapping mechanism at the p+-Si/n-ZnO interface barrier region is presented to explain the light-induced conductance potentiation/depression behavior. Furthermore, some synaptic functions, including excitatory postsynaptic current (EPSC), inhibitory postsynaptic current (IPSC), and paired-pulse facilitation (PPF), are successfully mimicked in the p+-Si/n-ZnO heterojunction memristor, instructing its application potential for optoelectronic neuromorphic computing.
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Affiliation(s)
- Xinmiao Li
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Zijing Fang
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Xing Guo
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Ruixiao Wang
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Yinxi Zhao
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Wenhui Zhu
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Liancheng Wang
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
| | - Lei Zhang
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410000, China
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3
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Jeffries WR, Jawaid AM, Vaia RA, Knappenberger KL. Thickness-dependent electronic relaxation dynamics in solution-phase redox-exfoliated MoS2 heterostructures. J Chem Phys 2024; 160:144707. [PMID: 38597312 DOI: 10.1063/5.0200398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 03/20/2024] [Indexed: 04/11/2024] Open
Abstract
Electronic relaxation dynamics of solution-phase redox-exfoliated molybdenum disulfide (MoS2) monolayer and multilayer ensembles are described. MoS2 was exfoliated using polyoxometalate (POM) reductants. This process yields a colloidal heterostructure consisting of MoS2 2D sheet multilayers with surface-bound POM complexes. Using two-dimensional electronic spectroscopy, transient bleaching and photoinduced absorption signals were detected at excitation/detection energies of 1.82/1.87 and 1.82/1.80 eV, respectively. Approximate 100-fs bandgap renormalization (BGR) and subsequent defect- and phonon-mediated relaxation on the picosecond timescale were resolved for several MoS2 thicknesses spanning from 1 to 2 L to ∼20 L. BGR rates were independent of sample thickness and slightly slower than observations for chemical vapor deposition-grown MoS2 monolayers. However, defect-mediated relaxation accelerated ∼10-fold with increased sample thicknesses. The relaxation rates increased from 0.33 ± 0.05 to 1.2 ± 0.1 and 3.1 ± 0.4 ps-1 for 1-2 L, 3-4 L, and 20 L fractions. The thicknesses-dependent relaxation rates for POM-MoS2 heterostructures were modeled using a saturating exponential function that showed saturation at thirteen MoS2 layers. The results suggest that the increased POM surface coverage leads to larger defect density in the POM-MoS2 heterostructure. These are the first descriptions of the influence of sample thickness on electronic relaxation rates in solution-phase redox-exfoliated POM-MoS2 heterostructures. Outcomes of this work are expected to impact the development of solution-phase exfoliation of 2D metal-chalcogenide heterostructures.
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Affiliation(s)
- William R Jeffries
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ali M Jawaid
- Air Force Research Laboratory, 2941 Hobson Way, Wright Patterson Air Force Base, Dayton, Ohio 45433, USA
| | - Richard A Vaia
- Air Force Research Laboratory, 2941 Hobson Way, Wright Patterson Air Force Base, Dayton, Ohio 45433, USA
| | - Kenneth L Knappenberger
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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4
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Ma S, Li G, Li Z, Wang T, Zhang Y, Li N, Chen H, Zhang N, Liu W, Huang Y. Negative Photoconductivity of Fe 3GeTe 2 Crystal with Native Heterostructure for Ultraviolet to Terahertz Ultra-Broadband Photodetection. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305709. [PMID: 38207342 DOI: 10.1002/adma.202305709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 12/10/2023] [Indexed: 01/13/2024]
Abstract
Gaining insight into the photoelectric behavior of ferromagnetic materials is significant for comprehensively grasping their intrinsic properties and broadening future application fields. Here, through a specially designed Fe3GeTe2/O-Fe3GeTe2 heterostructure, first, the broad-spectrum negative photoconductivity phenomenon of ferromagnetic nodal line semimetal Fe3GeTe2 is reported that covers UV-vis-infrared-terahertz bands (355 nm to 3000 µm), promising to compensate for the inadequacies of traditional optoelectronic devices. The significant suppression of photoexcitation conductivity is revealed to arise from the semimetal/oxidation (sMO) interface-assisted dual-response mechanism, in which the electron excitation origins from the semiconductor photoconductivity effect in high-energy photon region, and semimetal topological band-transition in low-energy photon region. High responsivities ranging from 103 to 100 mA W-1 are acquired within ultraviolet-terahertz bands under ±0.1 V bias voltage at room temperature. Notably, the responsivity of 2.572 A W-1 at 3000 µm (0.1 THz) and the low noise equivalent power of 26 pW Hz-1/2 surpass most state-of-the-art mainstream terahertz detectors. This research provides a new perspective for revealing the photoelectric conversion properties of Fe3GeTe2 crystal and paves the way for the development of spin-optoelectronic devices.
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Affiliation(s)
- Suping Ma
- National Institute for Advanced Materials, Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Functional Polymer Materials, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Guanghao Li
- National Institute for Advanced Materials, Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Functional Polymer Materials, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Zhuo Li
- National Institute for Advanced Materials, Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Functional Polymer Materials, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Tingyuan Wang
- Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Nankai University, Tianjin, 300350, P. R. China
| | - Yawen Zhang
- National Institute for Advanced Materials, Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Functional Polymer Materials, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Ningning Li
- Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Nankai University, Tianjin, 300350, P. R. China
| | - Haisheng Chen
- Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Nankai University, Tianjin, 300350, P. R. China
| | - Nan Zhang
- Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Nankai University, Tianjin, 300350, P. R. China
| | - Weiwei Liu
- Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Nankai University, Tianjin, 300350, P. R. China
| | - Yi Huang
- National Institute for Advanced Materials, Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Key Laboratory of Functional Polymer Materials, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
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5
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Handa T, Holbrook M, Olsen N, Holtzman LN, Huber L, Wang HI, Bonn M, Barmak K, Hone JC, Pasupathy AN, Zhu X. Spontaneous exciton dissociation in transition metal dichalcogenide monolayers. SCIENCE ADVANCES 2024; 10:eadj4060. [PMID: 38295176 PMCID: PMC10830119 DOI: 10.1126/sciadv.adj4060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 12/28/2023] [Indexed: 02/02/2024]
Abstract
Since the seminal work on MoS2, photoexcitation in atomically thin transition metal dichalcogenides (TMDCs) has been assumed to result in excitons, with binding energies order of magnitude larger than thermal energy at room temperature. Here, we reexamine this foundational assumption and show that photoexcitation of TMDC monolayers can result in a substantial population of free charges. Performing ultrafast terahertz spectroscopy on large-area, single-crystal TMDC monolayers, we find that up to ~10% of excitons spontaneously dissociate into charge carriers with lifetimes exceeding 0.2 ns. Scanning tunneling microscopy reveals that photocarrier generation is intimately related to mid-gap defects, likely via trap-mediated Auger scattering. Only in state-of-the-art quality monolayers, with mid-gap trap densities as low as 109 cm-2, does intrinsic exciton physics start to dominate the terahertz response. Our findings reveal the necessity of knowing the defect density in understanding photophysics of TMDCs.
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Affiliation(s)
- Taketo Handa
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Madisen Holbrook
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Nicholas Olsen
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Luke N. Holtzman
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA
| | - Lucas Huber
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Hai I. Wang
- Max Planck Institute for Polymer Research, Mainz 55128, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Mainz 55128, Germany
| | - Katayun Barmak
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA
| | - James C. Hone
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | | | - Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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6
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Ji J, Zhou Y, Zhou B, Desgué E, Legagneux P, Jepsen PU, Bøggild P. Probing Carrier Dynamics in Large-Scale MBE-Grown PtSe 2 Films by Terahertz Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37883033 DOI: 10.1021/acsami.3c09792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
Atomically thin platinum diselenide (PtSe2) films are promising for applications in the fields of electronics, spintronics, and photodetectors owing to their tunable electronic structure and high carrier mobility. Using terahertz (THz) spectroscopy techniques, we investigated the layer-dependent semiconducting-to-metallic phase transition and associated intrinsic carrier dynamics in large-scale PtSe2 films grown by molecular beam epitaxy. The uniformity of large-scale PtSe2 films was characterized by spatially and frequency-resolved THz-based sheet conductivity mapping. Furthermore, we use an optical-pump-THz-probe technique to study the transport dynamics of photoexcited carriers and explore light-induced intergrain carrier transport in PtSe2 films. We demonstrate large-scale THz-based mapping of the electrical properties of transition metal dichalcogenide films and show that the two noncontact THz-based approaches provide insight in the spatial and temporal properties of PtSe2 films.
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Affiliation(s)
- Jie Ji
- Department of Physics, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Yingqiu Zhou
- Department of Physics, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Binbin Zhou
- Department of Electrical and Photonics Engineering, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Eva Desgué
- Thales Research and Technology, Palaiseau 91767, France
| | | | - Peter Uhd Jepsen
- Department of Electrical and Photonics Engineering, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Peter Bøggild
- Department of Physics, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
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7
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Sayer T, Farah YR, Austin R, Sambur J, Krummel AT, Montoya-Castillo A. Trion Formation Resolves Observed Peak Shifts in the Optical Spectra of Transition-Metal Dichalcogenides. NANO LETTERS 2023. [PMID: 37311112 DOI: 10.1021/acs.nanolett.3c01342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Monolayer transition-metal dichalcogenides (ML-TMDs) have the potential to unlock novel photonic and chemical technologies if their optoelectronic properties can be understood and controlled. Yet, recent work has offered contradictory explanations for how TMD absorption spectra change with carrier concentration, fluence, and time. Here, we test our hypothesis that the large broadening and shifting of the strong band-edge features observed in optical spectra arise from the formation of negative trions. We do this by fitting an ab initio based, many-body model to our experimental electrochemical data. Our approach provides an excellent, global description of the potential-dependent linear absorption data. We further leverage our model to demonstrate that trion formation explains the nonmonotonic potential dependence of the transient absorption spectra, including through photoinduced derivative line shapes for the trion peak. Our results motivate the continued development of theoretical methods to describe cutting-edge experiments in a physically transparent way.
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Affiliation(s)
- Thomas Sayer
- Department of Chemistry, University of Colorado Boulder, Boulder 80309, Colorado, United States
| | - Yusef R Farah
- Department of Chemistry, Colorado State University, Fort Collins 80523, Colorado, United States
| | - Rachelle Austin
- Department of Chemistry, Colorado State University, Fort Collins 80523, Colorado, United States
| | - Justin Sambur
- Department of Chemistry, Colorado State University, Fort Collins 80523, Colorado, United States
- School of Advanced Materials Discovery, Colorado State University, Fort Collins 80524, Colorado, United States
| | - Amber T Krummel
- Department of Chemistry, Colorado State University, Fort Collins 80523, Colorado, United States
| | - Andrés Montoya-Castillo
- Department of Chemistry, University of Colorado Boulder, Boulder 80309, Colorado, United States
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8
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Fu J, Ramesh S, Melvin Lim JW, Sum TC. Carriers, Quasi-particles, and Collective Excitations in Halide Perovskites. Chem Rev 2023. [PMID: 37276018 DOI: 10.1021/acs.chemrev.2c00843] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Halide perovskites (HPs) are potential game-changing materials for a broad spectrum of optoelectronic applications ranging from photovoltaics, light-emitting devices, lasers to radiation detectors, ferroelectrics, thermoelectrics, etc. Underpinning this spectacular expansion is their fascinating photophysics involving a complex interplay of carrier, lattice, and quasi-particle interactions spanning several temporal orders that give rise to their remarkable optical and electronic properties. Herein, we critically examine and distill their dynamical behavior, collective interactions, and underlying mechanisms in conjunction with the experimental approaches. This review aims to provide a unified photophysical picture fundamental to understanding the outstanding light-harvesting and light-emitting properties of HPs. The hotbed of carrier and quasi-particle interactions uncovered in HPs underscores the critical role of ultrafast spectroscopy and fundamental photophysics studies in advancing perovskite optoelectronics.
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Affiliation(s)
- Jianhui Fu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Sankaran Ramesh
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Energy Research Institute @NTU (ERI@N), Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
| | - Jia Wei Melvin Lim
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Energy Research Institute @NTU (ERI@N), Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
| | - Tze Chien Sum
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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9
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Kinha M, Dagar R, Sahoo J, Rakshit R, Rana DS. Observation of negative terahertz photoconductivity in strongly correlated electron-doped CaMnO 3thin film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35. [PMID: 37080209 DOI: 10.1088/1361-648x/acceef] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/20/2023] [Indexed: 05/03/2023]
Abstract
Electron-doped Ca0.96Ce0.04MnO3(CCMO) possesses a unique band structure and exhibits a giant topological Hall effect contrary to other correlation-driven manganites known for insulator-to-metal transition, magnetoresistance, complex magnetic order, etc. The interaction mechanisms among the fundamental entities and their dynamical evolutions responsible for this unusual topological phase are yet to be understood. Here, we employ time-averaged and sub-picosecond time-resolved terahertz (THz) spectroscopy to explore the low-energy steady-state and ultrafast carrier dynamics, respectively, to unravel the complexity of charge carriers during their transition from a non-equilibrium state to the ground state in CCMO thin film. The THz optical conductivity confirms the presence of dichotomic charge carriers, i.e. heavy and light carriers throughout the temperature range of 15-300 K. A rare observation of both positive and negative photoconductivities along with a sharp crossover between the two resolved to a few picoseconds of illumination confirms the formation of polaron with a lifetime of a few nanoseconds. These optical evidences of dichotomic charge carriers, along with manipulation of the sign of photoconductivity induced by dynamics of related quasiparticles could facilitate a new mechanism for ultrafast optoelectronic switching devices.
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Affiliation(s)
- Monu Kinha
- Department of Physics, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, Madhya Pradesh, India
| | - Rahul Dagar
- Department of Physics, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, Madhya Pradesh, India
| | - Jayaprakash Sahoo
- Department of Physics, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, Madhya Pradesh, India
| | - Rupali Rakshit
- Solid State and Structural Chemistry Unit, Indian Institute of Science, CV Raman Road, Bengaluru 560012, Karnataka, India
| | - D S Rana
- Department of Physics, Indian Institute of Science Education and Research Bhopal, Bhopal 462066, Madhya Pradesh, India
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10
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Huang Y, Lv S, Liu H, Cheng Q, Biao Y, Lu H, Lin X, Wang Z, Yang H, Chen H, Weng YX. Observation of photoinduced polarons in semimetal 1T-TiSe 2. NANOTECHNOLOGY 2023; 34:235707. [PMID: 36877995 DOI: 10.1088/1361-6528/acc188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/05/2023] [Indexed: 06/18/2023]
Abstract
In this work, ultrafast carrier dynamics of mechanically exfoliated 1T-TiSe2flakes from the high-quality single crystals with self-intercalated Ti atoms are investigated by femtosecond transient absorption spectroscopy. The observed coherent acoustic and optical phonon oscillations after ultrafast photoexcitation reveal the strong electron-phonon coupling in 1T-TiSe2. The ultrafast carrier dynamics probed in both visible and mid-infrared regions indicate that some photogenerated carriers localize near the intercalated Ti atoms and form small polarons rapidly within several picoseconds after photoexcitation due to the strong and short-range electron-phonon coupling. The formation of polarons leads to a reduction of carrier mobility and a long-time relaxation process of photoexcited carriers for several nanoseconds. The formation and dissociation rates of the photoinduced polarons are dependent on both the pump fluence and the thickness of TiSe2sample. This work offers new insights into the photogenerated carrier dynamics of 1T-TiSe2, and emphasizes the effects of intercalated atoms on the electron and lattice dynamics after photoexcitation.
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Affiliation(s)
- Yin Huang
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Senhao Lv
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Heyuan Liu
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Qiuzhen Cheng
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yi Biao
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Hongliang Lu
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Xiao Lin
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Zhuan Wang
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Haitao Yang
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, People's Republic of China
| | - Hailong Chen
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, People's Republic of China
| | - Yu-Xiang Weng
- Beijing National Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, People's Republic of China
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11
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Paramanik S, Pal AJ. Combining negative photoconductivity and resistive switching towards in-memory logic operations. NANOSCALE 2023; 15:5001-5010. [PMID: 36786743 DOI: 10.1039/d3nr00278k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
A family of rudorffites based on silver-bismuth-iodide shows a transition from a conventional positive photoconductivity (PPC) to an unusual negative photoconductivity (NPC) upon variation in the precursor stoichiometry while forming the rudorffites. The NPC has arisen in silver-rich rudorffites due to the generation of illumination-induced trap-states which prompted the recombination of charge carriers and thereby a decrease in the conductivity of the compounds. In addition to photoconductivity, sandwiched devices based on all the rudorffites exhibited resistive switching between a pristine high resistive state (HRS) and a low resistive state (LRS) under a suitable voltage pulse; the switching process, which is reversible, is associated with a memory phenomenon. The devices based on NPC-exhibiting rudorffites switched to the HRS under illumination as well. That is, the resistive state of the devices could be controlled through both electrical and optical inputs. We employed such interesting optoelectronic properties of NPC-exhibiting rudorffites to exhibit OR logic gate operation. Because the devices could function as a logic gate and store the resistive state as well, we concluded that the materials could be an ideal candidate for in-memory logic operations.
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Affiliation(s)
- Subham Paramanik
- School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Amlan J Pal
- School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001, India
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12
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Heliso Dolla T, Matthews T, Wendy Maxakato N, Ndungu P, Montini T. Recent advances in transition metal sulfide-based electrocatalysts and photocatalysts for nitrogen fixation. J Electroanal Chem (Lausanne) 2023. [DOI: 10.1016/j.jelechem.2022.117049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Zhang W, Sun K, Suo P, Yan X, Lin X, Jin Z, Ma G. Ultrafast Photocarrier Dynamics in Vertically Aligned SnS 2 Nanoflakes Probing with Transient Terahertz Spectroscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:5. [PMID: 36615915 PMCID: PMC9824797 DOI: 10.3390/nano13010005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/18/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
By employing optical pump Terahertz (THz) probe spectroscopy, ultrafast photocarrier dynamics of a two-dimensional (2D) semiconductor, SnS2 nanoflake film, has been investigated systematically at room temperature. The dynamics of photoexcitation is strongly related to the density of edge sites and defects in the SnS2 nanoflakes, which is controllable by adjusting the height of vertically aligned SnS2 during chemical vapor deposition growth. After photoexcitation at 400 nm, the transient THz photoconductivity response of the films can be well fitted with bi-exponential decay function. The fast and slow processes are shorter in the thinner film than in the thicker sample, and both components are independent on the pump fluence. Hereby, we propose that edge-site trapping as well as defect-assisted electron-hole recombination are responsible for the fast and slow decay progress, respectively. Our experimental results demonstrate that the edge sites and defects in SnS2 nanoflakes play a dominant role in photocarrier relaxation, which is crucial in understanding the photoelectrochemical performance of SnS2 nanoflakes.
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Affiliation(s)
| | | | | | | | | | | | - Guohong Ma
- Department of Physics, Shanghai University, Shanghai 200444, China
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14
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Li M, Ma X, Mu Y, Xie G, Wan H, Tao M, Guo B, Gong JR. A facile covalent strategy for ultrafast negative photoconductance hybrid graphene/porphyrin-based photodetector. NANOTECHNOLOGY 2022; 34:085201. [PMID: 36541533 DOI: 10.1088/1361-6528/aca598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
As a powerful complement to positive photoconductance (PPC), negative photoconductance (NPC) holds great potential for photodetector. However, the slow response of NPC relative to PPC devices limits their integration. Here, we propose a facile covalent strategy for an ultrafast NPC hybrid 2D photodetector. Our transistor-based graphene/porphyrin model device with a rise time of 0.2 ms and decay time of 0.3 ms has the fastest response time in the so far reported NPC hybrid photodetectors, which is attributed to efficient photogenerated charge transport and transfer. Both the photosensitive porphyrin with an electron-rich and large rigid structure and the built-in graphene frame with high carrier mobility are prone to the photogenerated charge transport. Especially, the intramolecular donor-acceptor system formed by graphene and porphyrin through covalent bonding promotes photoinduced charge transfer. This covalent strategy can be applied to other nanosystems for high-performance NPC hybrid photodetector.
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Affiliation(s)
- Mengshan Li
- Department of Chemistry, School of Science Tianjin University, Weijin Road, Tianjin 300072, People's Republic of China
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Xiaoqing Ma
- Department of Chemistry, School of Science Tianjin University, Weijin Road, Tianjin 300072, People's Republic of China
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Yanqi Mu
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- University of CAS, Beijing 100190, People's Republic of China
| | - Guancai Xie
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- University of CAS, Beijing 100190, People's Republic of China
| | - Hongfeng Wan
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- University of CAS, Beijing 100190, People's Republic of China
| | - Minli Tao
- Department of Chemistry, School of Science Tianjin University, Weijin Road, Tianjin 300072, People's Republic of China
| | - Beidou Guo
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- University of CAS, Beijing 100190, People's Republic of China
| | - Jian Ru Gong
- Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchy Fabrication, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
- University of CAS, Beijing 100190, People's Republic of China
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15
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Wang PJ, Tsai PC, Yang ZS, Lin SY, Sun CK. Revealing the interlayer van der Waals coupling of bi-layer and tri-layer MoS 2 using terahertz coherent phonon spectroscopy. PHOTOACOUSTICS 2022; 28:100412. [PMID: 36281319 PMCID: PMC9587369 DOI: 10.1016/j.pacs.2022.100412] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/20/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
In this research, we applied THz coherent phonon spectroscopy to optically probe the vibrational modes of the epitaxially-grown bi-layer and tri-layer MoS2 on sapphire substrate. The layers' THz vibration is displacively stimulated and temporally retrieved by near-UV femtosecond laser pulses, revealing Raman-active and Raman-inactive modes in one measurement. With the complete breathing modes revealed, here we extend the linear chain model by considering the elastic contact with the substrate and vdWs coupling of the next nearest MoS2 layer to analyze the effective spring constants. We further considered the intralayer stiffness as a correction term to acquire the actual interlayer vdWs coupling. Our THz phonon spectroscopy results indicate the interlayer spring constants of 9.03 × 1019 N/m3 and 9.86 × 1019 N/m3 for bi-layer and tri-layer respectively. The extended model further suggests that a non-negligible substrate mechanical coupling and next nearest neighbor vdWs coupling of 1.48 × 1019 N/m3 and 1.04 × 1019 N/m3 have to be considered.
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Affiliation(s)
- Peng-Jui Wang
- Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Po-Cheng Tsai
- Graduate Institute of Electronics Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan
- Research Center for Applied Sciences, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Zih-Sian Yang
- Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Shih-Yen Lin
- Graduate Institute of Electronics Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan
- Research Center for Applied Sciences, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Chi-Kuang Sun
- Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
- Research Center for Applied Sciences, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
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16
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Yin Y, Ling J, Wang L, Zhou W, Peng Y, Zhou Y, Tang D. Competition of Photo-Excitation and Photo-Desorption Induced Positive and Negative Photoconductivity Switch in Te Nanowires. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3747. [PMID: 36364522 PMCID: PMC9656629 DOI: 10.3390/nano12213747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/13/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
The photocurrent in tellurium nanowire (Te NW) exhibits a subtle influence by many extrinsic factors. Herein, we fabricate Te NW devices and explore their photoresponse properties in detail. It is observed that the current increases greatly at low environmental relative humidity (RH) under light illumination, demonstrating an evident positive photoconductivity (PPC). However, the photocurrent reduces at high RH, yielding a typical negative photoconductivity (NPC). In addition, when exposed to a proper relative humidity, Te NW devices show PPC immediately and then transfer to NPC gradually under illumination, exhibiting the RH sensitive PPC/NPC switch. It is proposed that the competition between photo-excitation and photo-desorption is responsible for this subtle switch of PPC/NPC. On the one hand, the adsorbed water molecules on the surface of Te nanowires, acting as electron acceptors, lead to an increase of conductance, exhibiting the PPC phenomenon. On the other hand, the photo-desorption of water molecules from the surface results in a decreased carrier concentration in the Te nanowires, yielding the NPC phenomenon. The in-depth understanding of such charge transfer processes between the absorbed water molecules and Te nanowires provides an effective route to modulate the carrier densities and control the PPC/NPC switch, which will accelerate the design and application of novel optoelectronic nanodevices.
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17
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Zhumagulov YV, Vagov A, Gulevich DR, Perebeinos V. Electrostatic and Environmental Control of the Trion Fine Structure in Transition Metal Dichalcogenide Monolayers. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3728. [PMID: 36364505 PMCID: PMC9656490 DOI: 10.3390/nano12213728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Charged excitons or trions are essential for optical spectra in low-dimensional doped monolayers (ML) of transitional metal dichalcogenides (TMDC). Using a direct diagonalization of the three-body Hamiltonian, we calculate the low-lying trion states in four types of TMDC MLs as a function of doping and dielectric environment. We show that the fine structure of the trion is the result of the interplay between the spin-valley fine structure of the single-particle bands and the exchange interaction. We demonstrate that by variations of the doping and dielectric environment, the fine structure of the trion energy can be tuned, leading to anticrossing of the bright and dark states, with substantial implications for the optical spectra of the TMDC ML.
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Affiliation(s)
| | - Alexei Vagov
- Faculty of Physics, National Research University Higher School of Economics, 101000 Moscow, Russia
| | | | - Vasili Perebeinos
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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18
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Wang R, Wang JL, Liu T, He Z, Wang H, Liu JW, Yu SH. Controllable Inverse Photoconductance in Semiconducting Nanowire Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204698. [PMID: 35854411 DOI: 10.1002/adma.202204698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/02/2022] [Indexed: 06/15/2023]
Abstract
As a typical p-type semiconductor, tellurium (Te) has been widely studied for the construction of photodetectors. However, only the positive photoconductance of Te-based photodetectors based on the photoconductive effect has been observed in the reported literature. Herein, an unusual but interesting phenomenon, in that tellurium nanowires (NWs) behave with negative photoresponse to positive photoresponse under enlarged optical intensities from the UV to VIS-IR region is reported. According to the experiments and simulations, adsorbed oxygen on the surface of Te NWs plays a significant role in the abnormal photoresponse. The inverse photoconductance can be attributed to the competition between the photoconductive effect and the oxygen desorption effect. Moreover, the influence of the size and layers of Te NWs is also discussed. This inverse photoconductance phenomenon is further explored by introducing the Te-Au heterojunction system. Hot-electron injection at the Te-Au heterojunction interface induces a more obvious tendency to behave with a negative photoresponse. These findings will be beneficial for potential applications of Te-NW-based photodetectors.
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Affiliation(s)
- Rui Wang
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
| | - Jin-Long Wang
- Institute of Innovative Materials (I2M), Department of Materials Science and Engineering, Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Tian Liu
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
| | - Zhen He
- Institute of Innovative Materials (I2M), Department of Materials Science and Engineering, Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Heng Wang
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
| | - Jian-Wei Liu
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
| | - Shu-Hong Yu
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, China
- Institute of Innovative Materials (I2M), Department of Materials Science and Engineering, Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, China
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19
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Adhikari P, Wang P, Kobbekaduwa K, Xie C, Huai C, Wang Y, Zhang J, Shi Y, Zheng H, Rao AM, Zeng H, Gao J. Generating and Capturing Secondary Hot Carriers in Monolayer Tungsten Dichalcogenides. J Phys Chem Lett 2022; 13:5703-5710. [PMID: 35713478 DOI: 10.1021/acs.jpclett.2c01073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
It remains challenging to capture and investigate the drift dynamics of primary hot carriers because of their ultrashort lifetime (∼200 fs). Here we report a new mechanism for secondary hot carrier (∼25 ps) generation in monolayer transition metal dichalcogenides such as WS2 and WSe2, triggered by the Auger recombination of trions and biexcitons. Using ultrafast photocurrent spectroscopy, we measured and characterized the photocurrent stemming from the Auger recombination of trions and biexcitons in WS2 and WSe2. A mobility of 0.24 cm2 V-1 s-1 and a drift length of ∼3.8 nm were found for the secondary hot carriers in WS2. By leveraging interactions between exciton complexes, we envision a new mechanism for generating and controlling hot carriers, which could lead to efficient devices in photophysics, photochemistry, and photosynthesis.
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Affiliation(s)
- Pan Adhikari
- Ultrafast Photophysics of Quantum Devices Laboratory, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - Peijian Wang
- Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260, United States
| | - Kanishka Kobbekaduwa
- Ultrafast Photophysics of Quantum Devices Laboratory, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - Chendi Xie
- Ultrafast Photophysics of Quantum Devices Laboratory, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - Chang Huai
- Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260, United States
| | - Yinghui Wang
- Femtosecond Laser Laboratory, Key Laboratory of Physics and Technology for Advanced Batteries, College of Physics, Jilin University, Changchun 130012, P. R. China
| | - Jianbing Zhang
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Ying Shi
- Institute of Atomic and Molecular Physics, Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, Changchun 130012, P. R. China
| | - Haimei Zheng
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Apparao M Rao
- Ultrafast Photophysics of Quantum Devices Laboratory, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
| | - Hao Zeng
- Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260, United States
| | - Jianbo Gao
- Ultrafast Photophysics of Quantum Devices Laboratory, Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States
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20
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Hight-Huf N, Pagaduan JN, Katsumata R, Emrick T, Barnes MD. Stabilization of Three-Particle Excitations in Monolayer MoS 2 by Fluorinated Methacrylate Polymers. J Phys Chem Lett 2022; 13:4794-4799. [PMID: 35613709 DOI: 10.1021/acs.jpclett.2c01150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
While extrinsic factors, such as substrates and chemical doping, are known to strongly influence visible photoemission from monolayer MoS2, key fundamental knowledge for p-type polymeric dopants is lacking. We investigated perturbations to the electronic environment of 2D MoS2 using fluorinated polymer coatings and specifically studied stabilization of three-particle states by monitoring changes in intensities and emission maxima of three-particle and two-particle emissions. We calculated changes in carrier density and trion binding energy, the latter having an additional contribution from MoS2 polarization by the polymer. Polarization is further suggested by Kelvin probe force microscopy (KPFM) measurements of large Fermi level shifts. Changes similar in magnitude, but opposite in sign, were observed in 2D MoS2 coated with an analogous nonfluorinated polymer. These findings highlight the important interplay between electron exchange and electrostatic interactions at the interface between polymers and transition metal dichalcogenides (TMDCs), which govern fundamental electronic properties relevant to next-generation devices.
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21
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Xing X, Zhang Z, Quan C, Zhao L, Wang C, Jia T, Ren J, Du J, Leng Y. Tunable ultrafast electron transfer in WSe 2-graphene heterostructures enabled by atomic stacking order. NANOSCALE 2022; 14:7418-7425. [PMID: 35543212 DOI: 10.1039/d1nr07698a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Efficient interfacial light-electric interconversion in van der Waals (vdW) heterostructures is crucial for their optoelectronic applications. However, an in-depth understanding of the necessary process for device operation, namely interfacial charge transfer (CT), has thus far remained elusive. In this study, by using photon energy-dependent transient THz spectroscopy, we complementarily investigate the interfacial CT process in heterostructures comprising monolayers of WSe2 and graphene with varying stacking orders on a sapphire substrate. We observe that the CT mechanism of the sub-A-exciton excitation is different from that of the above-A-exciton excitation. Notably, the CT process occurs via a photo-thermionic emission for sub-A-exciton excitations and a direct electron (or hole) transfer for above-A-exciton excitations. Furthermore, we demonstrate that the effective electric field induced by the sapphire substrate could adjust the Schottky barrier from a p-type contact (WSe2/Gr/sapphire) to an n-type contact (Gr/WSe2/sapphire). Consequently, it is more beneficial for the photo-thermionic electrons to transfer from graphene to WSe2 over the Schottky barrier in Gr/WSe2/sapphire. These results can provide new insights into the CT process in graphene-transition metal dichalcogenide (TMDC) vdW interfaces, which are critical to potential optoelectronic applications of graphene-TMDC heterostructures.
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Affiliation(s)
- Xiao Xing
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
| | - Zeyu Zhang
- Hangzhou Institute for Advanced Study and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Chenjing Quan
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
- School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Litao Zhao
- Key Laboratory of Spin Electron and Nanomaterials of Anhui Higher Education Institutes, Suzhou University, Suzhou 234000, People's Republic of China
| | - Chunwei Wang
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
| | - Tingyuan Jia
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
| | - Junfeng Ren
- School of Physics and Electronics, Shandong Normal University, Jinan, 250014, China
| | - Juan Du
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
- Hangzhou Institute for Advanced Study and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Yuxin Leng
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
- Hangzhou Institute for Advanced Study and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Hangzhou 310024, China.
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22
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Bieniek M, Sadecka K, Szulakowska L, Hawrylak P. Theory of Excitons in Atomically Thin Semiconductors: Tight-Binding Approach. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:1582. [PMID: 35564291 PMCID: PMC9104105 DOI: 10.3390/nano12091582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/24/2022] [Accepted: 04/26/2022] [Indexed: 02/01/2023]
Abstract
Atomically thin semiconductors from the transition metal dichalcogenide family are materials in which the optical response is dominated by strongly bound excitonic complexes. Here, we present a theory of excitons in two-dimensional semiconductors using a tight-binding model of the electronic structure. In the first part, we review extensive literature on 2D van der Waals materials, with particular focus on their optical response from both experimental and theoretical points of view. In the second part, we discuss our ab initio calculations of the electronic structure of MoS2, representative of a wide class of materials, and review our minimal tight-binding model, which reproduces low-energy physics around the Fermi level and, at the same time, allows for the understanding of their electronic structure. Next, we describe how electron-hole pair excitations from the mean-field-level ground state are constructed. The electron-electron interactions mix the electron-hole pair excitations, resulting in excitonic wave functions and energies obtained by solving the Bethe-Salpeter equation. This is enabled by the efficient computation of the Coulomb matrix elements optimized for two-dimensional crystals. Next, we discuss non-local screening in various geometries usually used in experiments. We conclude with a discussion of the fine structure and excited excitonic spectra. In particular, we discuss the effect of band nesting on the exciton fine structure; Coulomb interactions; and the topology of the wave functions, screening and dielectric environment. Finally, we follow by adding another layer and discuss excitons in heterostructures built from two-dimensional semiconductors.
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Affiliation(s)
- Maciej Bieniek
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (K.S.); (L.S.); (P.H.)
- Department of Theoretical Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
| | - Katarzyna Sadecka
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (K.S.); (L.S.); (P.H.)
- Department of Theoretical Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Ludmiła Szulakowska
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (K.S.); (L.S.); (P.H.)
| | - Paweł Hawrylak
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (K.S.); (L.S.); (P.H.)
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23
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Ezendam S, Herran M, Nan L, Gruber C, Kang Y, Gröbmeyer F, Lin R, Gargiulo J, Sousa-Castillo A, Cortés E. Hybrid Plasmonic Nanomaterials for Hydrogen Generation and Carbon Dioxide Reduction. ACS ENERGY LETTERS 2022; 7:778-815. [PMID: 35178471 PMCID: PMC8845048 DOI: 10.1021/acsenergylett.1c02241] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 01/07/2022] [Indexed: 05/05/2023]
Abstract
The successful development of artificial photosynthesis requires finding new materials able to efficiently harvest sunlight and catalyze hydrogen generation and carbon dioxide reduction reactions. Plasmonic nanoparticles are promising candidates for these tasks, due to their ability to confine solar energy into molecular regions. Here, we review recent developments in hybrid plasmonic photocatalysis, including the combination of plasmonic nanomaterials with catalytic metals, semiconductors, perovskites, 2D materials, metal-organic frameworks, and electrochemical cells. We perform a quantitative comparison of the demonstrated activity and selectivity of these materials for solar fuel generation in the liquid phase. In this way, we critically assess the state-of-the-art of hybrid plasmonic photocatalysts for solar fuel production, allowing its benchmarking against other existing heterogeneous catalysts. Our analysis allows the identification of the best performing plasmonic systems, useful to design a new generation of plasmonic catalysts.
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Affiliation(s)
- Simone Ezendam
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Matias Herran
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Lin Nan
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Christoph Gruber
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Yicui Kang
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Franz Gröbmeyer
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Rui Lin
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Julian Gargiulo
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Ana Sousa-Castillo
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
| | - Emiliano Cortés
- Faculty
of Physics, Ludwig-Maximilians-Universität, 80539 München, Germany
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24
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Kozlova EA, Lyulyukin MN, Kozlov DV, Parmon VN. Semiconductor photocatalysts and mechanisms of carbon dioxide reduction and nitrogen fixation under UV and visible light. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr5004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Abstract
The review summarizes the current knowledge about heterogeneous semiconductor photocatalysts that are active towards photocatalytic reduction of carbon dioxide and molecular nitrogen under visible and near-UV light. The main classes of these photocatalysts and characteristic features of their application in the target processes are considered. Primary attention is given to photocatalysts based on titanium dioxide, which have high activity and stability in the carbon dioxide reduction. For the first time, the photofixation of nitrogen under irradiation in the presence of various semiconductor materials is considered in detail.
The bibliography includes 264 references.
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25
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Liu E, van Baren J, Lu Z, Taniguchi T, Watanabe K, Smirnov D, Chang YC, Lui CH. Exciton-polaron Rydberg states in monolayer MoSe 2 and WSe 2. Nat Commun 2021; 12:6131. [PMID: 34675213 PMCID: PMC8531338 DOI: 10.1038/s41467-021-26304-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/28/2021] [Indexed: 11/18/2022] Open
Abstract
Exciton polaron is a hypothetical many-body quasiparticle that involves an exciton dressed with a polarized electron-hole cloud in the Fermi sea. It has been evoked to explain the excitonic spectra of charged monolayer transition metal dichalcogenides, but the studies were limited to the ground state. Here we measure the reflection and photoluminescence of monolayer MoSe2 and WSe2 gating devices encapsulated by boron nitride. We observe gate-tunable exciton polarons associated with the 1 s–3 s exciton Rydberg states. The ground and excited exciton polarons exhibit comparable energy redshift (15~30 meV) from their respective bare excitons. The robust excited states contradict the trion picture because the trions are expected to dissociate in the excited states. When the Fermi sea expands, we observe increasingly severe suppression and steep energy shift from low to high exciton-polaron Rydberg states. Their gate-dependent energy shifts go beyond the trion description but match our exciton-polaron theory. Our experiment and theory demonstrate the exciton-polaron nature of both the ground and excited excitonic states in charged monolayer MoSe2 and WSe2. An exciton polaron is a quasiparticle composed of an exciton dressed with an electron-hole cloud, and this concept has been used to explain the ground excitonic states in charged monolayer transition metal dichalcogenides. Here the authors present experimental and theoretical evidence of exciton-polaron Rydberg states in monolayer MoSe2 and WSe2.
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Affiliation(s)
- Erfu Liu
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Jeremiah van Baren
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA
| | - Zhengguang Lu
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.,Department of Physics, Florida State University, Tallahassee, FL, 32310, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki, 305-0044, Japan
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki, 305-0044, Japan
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Yia-Chung Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan.
| | - Chun Hung Lui
- Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.
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26
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Yue YY, Zhao LY, Han DA, Wang L, Wang HY, Gao BR, Sun HB. Trion dynamics and charge photogeneration in MoS 2 nanosheets prepared by liquid phase exfoliation. Phys Chem Chem Phys 2021; 23:22430-22436. [PMID: 34585679 DOI: 10.1039/d1cp02455h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Since excitonic quasiparticles, including excitons, trions and charges, have a great influence on the photoelectric characteristics of two-dimensional (2D) transition metal dichalcogenides (TMDs), systematic explorations of the trion dynamics and charge photogeneration in 2D TMDs are important for their future optoelectronic applications. Here, broadband femtosecond transient absorption spectroscopic experiments are performed first to investigate the peak shifting and broadening kinetics in MoS2 nanosheets in solution prepared by liquid phase exfoliation (LPE-MoS2, ∼9 layers, 9L), which reveal that the binding energies for the A-, B-, and C-exciton states are ∼77 meV, ∼76 meV, and -70 meV (the energy difference between free charges and excitons; the negative sign for C-excitons means a spontaneous dissociation nature in band-nesting regions), respectively. Then, the trion dynamics and charge photogeneration in LPE-MoS2 nanosheets have been studied in detail, demonstrating that they are comparable to those in chemical vapor deposition grown MoS2 films (1L-, 3L- and 7L-MoS2). These experimental results suggest that LPE-TMD nanosheets also have the potential for use in charge-related optoelectronic devices based on 2D TMDs.
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Affiliation(s)
- Yuan-Yuan Yue
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China. .,School of Management Science and Information Engineering, Jilin University of Finance and Economics, Changchun 130117, China
| | - Le-Yi Zhao
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Dan-Ao Han
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Lei Wang
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Hai-Yu Wang
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Bing-Rong Gao
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Hong-Bo Sun
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Haidian, Beijing 100084, China
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27
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Cambré S, Liu M, Levshov D, Otsuka K, Maruyama S, Xiang R. Nanotube-Based 1D Heterostructures Coupled by van der Waals Forces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2102585. [PMID: 34355517 DOI: 10.1002/smll.202102585] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/19/2021] [Indexed: 06/13/2023]
Abstract
1D van der Waals heterostructures based on carbon nanotube templates are raising a lot of excitement due to the possibility of creating new optical and electronic properties, by either confining molecules inside their hollow core or by adding layers on the outside of the nanotube. In contrast to their 2D analogs, where the number of layers, atomic type and relative orientation of the constituting layers are the main parameters defining physical properties, 1D heterostructures provide an additional degree of freedom, i.e., their specific diameter and chiral structure, for engineering their characteristics. The current state-of-the-art in synthesizing 1D heterostructures are discussed here, in particular focusing on their resulting optical properties, and details the vast parameter space that can be used to design heterostructures with custom-built properties that can be integrated into a large variety of applications. First, the effects of van der Waals coupling on the properties of the simplest and best-studied 1D heterostructure, namely a double-walled carbon nanotube, are described, and then heterostructures built from the inside and the outside are considered, which all use a nanotube as a template, and, finally, an outlook is provided for the future of this research field.
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Affiliation(s)
- Sofie Cambré
- Nanostructured and Organic Optical and Electronic Materials, Department of Physics, University of Antwerp, Antwerp 2610, Belgium
| | - Ming Liu
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Dmitry Levshov
- Nanostructured and Organic Optical and Electronic Materials, Department of Physics, University of Antwerp, Antwerp 2610, Belgium
| | - Keigo Otsuka
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Shigeo Maruyama
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Rong Xiang
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
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28
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Zalipaev VV, Kuidin VV. Semiclassical approach for excitonic spectrum of Coulomb coupling between two Dirac particles. Proc Math Phys Eng Sci 2021. [DOI: 10.1098/rspa.2021.0098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The properties of the energy spectrum of excitons in monolayer transition metal dichalcogenides are investigated using a multiband model. In the multiband model, we use the excitonic Hamiltonian in the product base of the Dirac single-particle states at the conduction and valence band edges. Following the separation of variables, we decouple the corresponding energy eigenvalue system of the first-order ODE radial equations rigorously and solve the resulting second-order ODE self-consistently, using the finite difference method, thus we determine the energy eigenvalues of the discrete excitonic spectrum and the corresponding wave functions. We also developed a WKB approach to solve the same spectral problem in semiclassical approximation for the resulting ODE. We compare the results for the energy spectrum and the corresponding eigen-function forms for WS
2
and WSe
2
obtained by means of both methods. We also compare our results for the energy spectrum with other theoretical works for excitons, and with available experimental data.
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29
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Suo P, Zhang H, Yan S, Zhang W, Fu J, Lin X, Hao S, Jin Z, Zhang Y, Zhang C, Miao F, Liang SJ, Ma G. Observation of Negative Terahertz Photoconductivity in Large Area Type-II Dirac Semimetal PtTe_{2}. PHYSICAL REVIEW LETTERS 2021; 126:227402. [PMID: 34152189 DOI: 10.1103/physrevlett.126.227402] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 02/04/2021] [Accepted: 04/21/2021] [Indexed: 06/13/2023]
Abstract
As a newly emergent type-II Dirac semimetal, platinum telluride (PtTe_{2}) stands out from other two dimensional noble-transition-metal dichalcogenides for the unique band structure and novel physical properties, and has been studied extensively. However, the ultrafast response of low energy quasiparticle excitation in terahertz frequency remains nearly unexplored yet. Herein, we employ optical pump-terahertz probe (OPTP) spectroscopy to systematically study the photocarrier dynamics of PtTe_{2} thin films with varying pump fluence, temperature, and film thickness. Upon photoexcitation the terahertz photoconductivity (PC) of PtTe_{2} films shows abrupt increase initially, while the terahertz PC changes into negative value in a subpicosecond timescale, followed by a prolonged recovery process that lasted a few nanoseconds. The magnitude of both positive and negative terahertz PC response shows strongly pump fluence dependence. We assign the unusual negative terahertz PC to the formation of small polaron due to the strong electron-phonon (e-ph) coupling, which is further substantiated by temperature and film thickness dependent measurements. Moreover, our investigations give a subpicosecond timescale of simultaneous carrier cooling and polaron formation. The present study provides deep insights into the underlying dynamics evolution mechanisms of photocarrier in type-II Dirac semimetal upon photoexcitation, which is of crucial importance for designing PtTe_{2}-based optoelectronic devices.
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Affiliation(s)
- Peng Suo
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Huiyun Zhang
- College of Electronics and Information Engineering, Shandong University of Science and Technology, Qingdao 266590, China
| | - Shengnan Yan
- Institute of Brain-inspired Intelligence, National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Wenjie Zhang
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Jibo Fu
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Xian Lin
- Department of Physics, Shanghai University, Shanghai 200444, China
| | - Song Hao
- Institute of Brain-inspired Intelligence, National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Zuanming Jin
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, 516 JunGong Road, Shanghai 200093, China
- STU & SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
| | - Yuping Zhang
- College of Electronics and Information Engineering, Shandong University of Science and Technology, Qingdao 266590, China
| | - Chao Zhang
- School of Physics, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Feng Miao
- Institute of Brain-inspired Intelligence, National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Shi-Jun Liang
- Institute of Brain-inspired Intelligence, National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Guohong Ma
- Department of Physics, Shanghai University, Shanghai 200444, China
- STU & SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
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30
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Kumar S, Singh A, Nivedan A, Kumar S, Yun SJ, Lee YH, Tondusson M, Degert J, Oberle J, Freysz E. Sub‐bandgap activated charges transfer in a graphene‐MoS
2
‐graphene heterostructure. NANO SELECT 2021. [DOI: 10.1002/nano.202000159] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Sunil Kumar
- Femtosecond Spectroscopy and Nonlinear Photonics Laboratory Department of Physics Indian Institute of Technology Delhi New Delhi 110016 India
| | - Arvind Singh
- Femtosecond Spectroscopy and Nonlinear Photonics Laboratory Department of Physics Indian Institute of Technology Delhi New Delhi 110016 India
| | - Anand Nivedan
- Femtosecond Spectroscopy and Nonlinear Photonics Laboratory Department of Physics Indian Institute of Technology Delhi New Delhi 110016 India
| | - Sandeep Kumar
- Femtosecond Spectroscopy and Nonlinear Photonics Laboratory Department of Physics Indian Institute of Technology Delhi New Delhi 110016 India
| | - Seok Joon Yun
- Department of Energy Science Sungkyunkwan University (SKKU) Suwon 16419 Republic of Korea
| | - Young Hee Lee
- Department of Energy Science Sungkyunkwan University (SKKU) Suwon 16419 Republic of Korea
| | | | - Jérôme Degert
- CNRS, LOMA UMR 5798 Univ. Bordeaux Talence 33405 France
| | - Jean Oberle
- CNRS, LOMA UMR 5798 Univ. Bordeaux Talence 33405 France
| | - Eric Freysz
- CNRS, LOMA UMR 5798 Univ. Bordeaux Talence 33405 France
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31
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Qin JX, Yang XG, Lv CF, Li YZ, Chen XX, Zhang ZF, Zang JH, Yang X, Liu KK, Dong L, Shan CX. Humidity Sensors Realized via Negative Photoconductivity Effect in Nanodiamonds. J Phys Chem Lett 2021; 12:4079-4084. [PMID: 33881881 DOI: 10.1021/acs.jpclett.1c01011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Herein, the negative photoconductivity (NPC) effect has been observed in nanodiamonds (NDs) for the first time, and with illumination under a 660 nm laser lamp, the conductivity of the NDs decreases significantly. The NPC effect has been attributed to the trapping of carriers by the absorbed water molecules on the ND surfaces. A humidity sensor has been constructed based on the NPC effect of the NDs, and the sensitivity of the sensor can reach 106%, which is the highest value ever reported for carbon-based humidity sensors.
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Affiliation(s)
- Jin-Xu Qin
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Xi-Gui Yang
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Chao-Fan Lv
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Yi-Zhe Li
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Xue-Xia Chen
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Zhen-Feng Zhang
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Jin-Hao Zang
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Xun Yang
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Kai-Kai Liu
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Lin Dong
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Chong-Xin Shan
- Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
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32
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Liang Q, Zhang Q, Zhao X, Liu M, Wee ATS. Defect Engineering of Two-Dimensional Transition-Metal Dichalcogenides: Applications, Challenges, and Opportunities. ACS NANO 2021; 15:2165-2181. [PMID: 33449623 DOI: 10.1021/acsnano.0c09666] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Atomic defects, being the most prevalent zero-dimensional topological defects, are ubiquitous in a wide range of 2D transition-metal dichalcogenides (TMDs). They could be intrinsic, formed during the initial sample growth, or created by postprocessing. Despite the majority of TMDs being largely unaffected after losing chalcogen atoms in the outermost layer, a spectrum of properties, including optical, electrical, and chemical properties, can be significantly modulated, and potentially invoke applicable functionalities utilized in many applications. Hence, controlling chalcogen atomic defects provides an alternative avenue for engineering a wide range of physical and chemical properties of 2D TMDs. In this article, we review recent progress on the role of chalcogen atomic defects in engineering 2D TMDs, with a particular focus on device performance improvements. Various approaches for creating chalcogen atomic defects including nonstoichiometric synthesis and postgrowth treatment, together with their characterization and interpretation are systematically overviewed. The tailoring of optical, electrical, and magnetic properties, along with the device performance enhancement in electronic, optoelectronic, chemical sensing, biomedical, and catalytic activity are discussed in detail. Postformation dynamic evolution and repair of chalcogen atomic defects are also introduced. Finally, we offer our perspective on the challenges and opportunities in this field.
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Affiliation(s)
- Qijie Liang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Qian Zhang
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Xiaoxu Zhao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Meizhuang Liu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
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33
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Jin H, Chen Y, Zhang L, Wan R, Zou Z, Li H, Gao Y. Positive and negative photoconductivity characteristics in CsPbBr 3/graphene heterojunction. NANOTECHNOLOGY 2021; 32:085202. [PMID: 33157541 DOI: 10.1088/1361-6528/abc850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Broadband response photodetectors have received great research interest in optical sensing field. Usually, materials with positive photoconductivity (PPC) are general and the lack of negative photoconductivity (NPC) materials limits the application of photoelectric effect, especially in the broadband photodetecting field. Therefore, the finding of NPC materials is very important. Integrating PPC and NPC response into a single device is extremely meaningful to the development of broadband photodetector. In this work, we fabricated CsPbBr3 nanocrystals (NCs)-multilayered graphene heterojunction, which achieved persistent NPC response to ultra violet (300-390 nm) and PPC response to visible light (420-510 nm). The persistent NPC relies on the desorption of H2O vapor, and varies its intensity with the power intensity of laser. The PPC relies on the holes transmission from NCs to graphene. The recombination of NPC and PPC effect provides background knowledge for the development of broadband photodetector.
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Affiliation(s)
- Haonan Jin
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074, People's Republic of China
| | - Yibo Chen
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074, People's Republic of China
| | - Louwen Zhang
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074, People's Republic of China
| | - Rui Wan
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074, People's Republic of China
| | - Zhengguang Zou
- College of Materials Science and Engineering, Guangxi Key Laboratory of Optical and Electronic Materials and Devices, Guilin University of Technology, Guilin 541004, People's Republic of China
| | - Haixia Li
- Hubei Key Laboratory of Optical Information and Pattern Recognition School of Mathematics and Physics, Wuhan Institute of Technology, Wuhan 430205, People's Republic of China
| | - Yihua Gao
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan 430074, People's Republic of China
- College of Materials Science and Engineering, Guangxi Key Laboratory of Optical and Electronic Materials and Devices, Guilin University of Technology, Guilin 541004, People's Republic of China
- Hubei Key Laboratory of Optical Information and Pattern Recognition School of Mathematics and Physics, Wuhan Institute of Technology, Wuhan 430205, People's Republic of China
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34
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Shi H, Li M, Shi J, Zhang D, Fan Z, Zhang M, Liu L. Self-Assembled Peptide Nanofibers with Voltage-Regulated Inverse Photoconductance. ACS APPLIED MATERIALS & INTERFACES 2021; 13:1057-1064. [PMID: 33378176 DOI: 10.1021/acsami.0c18893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Inverse photoconductance is an uncommon phenomenon observed in selective low-dimensional materials, in which the electrical conductivity of the materials decreases under light illumination. The unique material property holds great promise for biomedical applications in photodetectors, photoelectric logic gates, and low-power nonvolatile memory, which remains a daunting challenge. Especially, tunable photoconductivity for biocompatible materials is highly desired for interfacing with biological systems but is less explored in organic materials. Here, we report nanofibers self-assembled with cyclo-tyrosine-tyrosine (cyclo-YY) having voltage-regulated inverse photoconductance and photoconductance. The peptide nanofibers can be switched back and forth by a bias voltage for imitating biological sensing in artificial vision and memory devices. A peptide optoelectronic resistive random access memory (PORRAM) device has also been fabricated using the nanofibers that can be electrically switched between long-term and short-term memory. The underlying mechanism of the reversible photoconductance is discussed in this paper. Due to the inherent biocompatibility of peptide materials, the reversible photoconductive nanofibers may have broad applications in sensing and storage for biotic and abiotic interfaces.
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Affiliation(s)
- Huiyao Shi
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Minglin Li
- Fujian Key Laboratory of Medical Instrumentation and Pharmaceutical Technology, Fuzhou 350108, China
- College of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350108, China
| | - Jialin Shi
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dindong Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Shenyang 110016, China
| | - Zhen Fan
- Department of Polymeric Materials, School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
- Institute for Advanced Study, Tongji University, Shanghai 200092, China
| | - Mingjun Zhang
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Lianqing Liu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110169, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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35
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Tebyetekerwa M, Zhang J, Xu Z, Truong TN, Yin Z, Lu Y, Ramakrishna S, Macdonald D, Nguyen HT. Mechanisms and Applications of Steady-State Photoluminescence Spectroscopy in Two-Dimensional Transition-Metal Dichalcogenides. ACS NANO 2020; 14:14579-14604. [PMID: 33155803 DOI: 10.1021/acsnano.0c08668] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors exhibit many important structural and optoelectronic properties, such as strong light-matter interactions, direct bandgaps tunable from visible to near-infrared regions, flexibility and atomic thickness, quantum-confinement effects, valley polarization possibilities, and so on. Therefore, they are regarded as a very promising class of materials for next-generation state-of-the-art nano/micro optoelectronic devices. To explore different applications and device structures based on 2D TMDs, intrinsic material properties, their relationships, and evolutions with fabrication parameters need to be deeply understood, very often through a combination of various characterization techniques. Among them, steady-state photoluminescence (PL) spectroscopy has been extensively employed. This class of techniques is fast, contactless, and nondestructive and can provide very high spatial resolution. Therefore, it can be used to obtain optoelectronic properties from samples of various sizes (from microns to centimeters) during the fabrication process without complex sample preparation. In this article, the mechanism and applications of steady-state PL spectroscopy in 2D TMDs are reviewed. The first part of this review details the physics of PL phenomena in semiconductors and common techniques to acquire and analyze PL spectra. The second part introduces various applications of PL spectroscopy in 2D TMDs. Finally, a broader perspective is discussed to highlight some limitations and untapped opportunities of PL spectroscopy in characterizing 2D TMDs.
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Affiliation(s)
- Mike Tebyetekerwa
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Jian Zhang
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zhen Xu
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Thien N Truong
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Zongyou Yin
- Research School of Chemistry, College of Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Yuerui Lu
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Seeram Ramakrishna
- Department of Mechanical Engineering, National University of Singapore, Singapore 119260, Singapore
| | - Daniel Macdonald
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Hieu T Nguyen
- Research School of Electrical, Energy, and Materials Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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36
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Shin HJ, Bae S, Sim S. Ultrafast Auger process in few-layer PtSe 2. NANOSCALE 2020; 12:22185-22191. [PMID: 33135719 DOI: 10.1039/d0nr05897a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Enhanced many-body interactions due to strong Coulomb interactions and quantum confinement are one of the most prominent features of two-dimensional systems. The Auger process is a representative many-body interaction typically observed in two-dimensional semiconductors, determining important physical properties of materials, such as carrier lifetime, photoconductivity, and emission quantum yield. Recently, platinum dichalcogenides, represented by PtSe2 and PtS2, have attracted great attention due to their superior air stability, thickness-dependent semimetal-to-semiconductor transition, and exotic magnetic characteristics. However, the Auger process in platinum dichalcogenides has not been investigated to date. Here, we utilized ultrafast optical-pump terahertz-probe spectroscopy to explore carrier dynamics in few-layer semiconducting PtSe2. Most of the excited carriers are trapped by defects within ∼10 ps after excitation due to high defect density. We overcome this challenge by raising the excitation intensity to saturate trap sites with carriers, and observed a many-body process involving the carriers that survived the rapid trapping. This process is not band-to-band Auger recombination, but rather defect-assisted Auger recombination in which free carriers interact with trapped carriers at defects. Theoretical simulations show that this three-body Auger process can be approximated as bimolecular recombination at the rate of ∼3.3 × 10-3 cm2 s-1. This work provides insights into the interplay between ultrafast many-body processes and defects in two-dimensional semiconductors.
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Affiliation(s)
- Hee Jun Shin
- Pohang Accelerator Laboratory, POSTECH, Pohang 37673, Korea
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37
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Chi Z, Chen HH, Chen Z, Chen HL. Unveiling defect-mediated carrier dynamics in few-layer MoS2 prepared by ion exchange method via ultrafast Vis-NIR-MIR spectroscopy. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2007123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Zhen Chi
- The Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Institute of Photo-biophysics, School of Physics and Electronics, Henan University, Kaifeng 475004, China
| | - Hui-hui Chen
- Department of Materials Physics and Chemistry, Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science and Engineering, Beijing Institute of Technology Institution, Beijing 100081, China
| | - Zhuo Chen
- Department of Materials Physics and Chemistry, Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science and Engineering, Beijing Institute of Technology Institution, Beijing 100081, China
| | - Hai-long Chen
- The Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan 523808, China
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38
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Zhumagulov YV, Vagov A, Gulevich DR, Faria Junior PE, Perebeinos V. Trion induced photoluminescence of a doped MoS2 monolayer. J Chem Phys 2020; 153:044132. [DOI: 10.1063/5.0012971] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yaroslav V. Zhumagulov
- ITMO University, St. Petersburg 197101, Russia
- University of Regensburg, Regensburg 93040, Germany
| | | | | | | | - Vasili Perebeinos
- ITMO University, St. Petersburg 197101, Russia
- Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA
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39
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Folpini G, Gatto L, Cortecchia D, Devetta M, Crippa G, Vozzi C, Stagira S, Petrozza A, Cinquanta E. Ultrafast charge carrier dynamics in quantum confined 2D perovskite. J Chem Phys 2020; 152:214705. [PMID: 32505161 DOI: 10.1063/5.0008608] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We studied the charge carrier dynamics in 2D perovskite NBT2PbI4 by ultrafast optical pump-THz probe spectroscopy. We observed a few ps long relaxation dynamics that can be ascribed to the band to band carrier recombination, in the absence of any contribution from many-body and trap assisted processes. The transient conductivity spectra show that the polaron dynamics is strongly modulated by the presence of a rich exciton population. The polarization field resulting from the exciton formation acts as the source of a restoring force that localizes polarons. This is revealed by the presence of a negative imaginary conductivity. Our results show that the dynamics of excitons in 2D perovskites at room temperature can be detected by monitoring their effect on the conductivity of the photoinduced polaronic carrier.
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Affiliation(s)
- Giulia Folpini
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Milano, Italy
| | - Lorenzo Gatto
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Daniele Cortecchia
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Milano, Italy
| | - Michele Devetta
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Gabriele Crippa
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Caterina Vozzi
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Salvatore Stagira
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Annamaria Petrozza
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Milano, Italy
| | - Eugenio Cinquanta
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
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40
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Liang Q, Zhang Q, Gou J, Song T, Chen H, Yang M, Lim SX, Wang Q, Zhu R, Yakovlev N, Tan SC, Zhang W, Novoselov KS, Wee ATS. Performance Improvement by Ozone Treatment of 2D PdSe 2. ACS NANO 2020; 14:5668-5677. [PMID: 32364379 DOI: 10.1021/acsnano.0c00180] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Atomic-scale defects in two-dimensional transition metal dichalcogenides (TMDs) often dominate their physical and chemical properties. Introducing defects in a controllable manner can tailor properties of TMDs. For example, chalcogen atom defects in TMDs were reported to trigger phase transition, induce ferromagnetism, and drive superconductivity. However, reported strategies to induce chalcogen atom defects including postgrowth annealing, laser irradiation, or plasma usually require high temperature (such as 500 °C) or cause unwanted structural damage. Here, we demonstrate low-temperature (60 °C) partial surface oxidation in 2D PdSe2 with low disorder and good stability. The combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations provide evidence of atomic-scale partial oxidation with both atomic resolution and chemical sensitivity. We also experimentally demonstrate that this controllable oxygen incorporation effectively tailors the electronic, optoelectronic, and catalytic activity of PdSe2. This work provides a pathway toward fine-tuning the physical and chemical properties of 2D TMDs and their applications in nanoelectronics, optoelectronics, and electrocatalysis.
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Affiliation(s)
- Qijie Liang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Qian Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117574, Singapore
| | - Jian Gou
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Tingting Song
- College of Physics and Space Science, China West Normal University, Nanchong 637002, China
| | - Hao Chen
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Ming Yang
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Sharon Xiaodai Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Qixing Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Rui Zhu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Nikolai Yakovlev
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Swee Ching Tan
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117574, Singapore
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Kostya S Novoselov
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117574, Singapore
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, Block S14, 6 Science Drive 2, Singapore 117546, Singapore
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41
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Burdanova MG, Kashtiban RJ, Zheng Y, Xiang R, Chiashi S, Woolley JM, Staniforth M, Sakamoto-Rablah E, Xie X, Broome M, Sloan J, Anisimov A, Kauppinen EI, Maruyama S, Lloyd-Hughes J. Ultrafast Optoelectronic Processes in 1D Radial van der Waals Heterostructures: Carbon, Boron Nitride, and MoS 2 Nanotubes with Coexisting Excitons and Highly Mobile Charges. NANO LETTERS 2020; 20:3560-3567. [PMID: 32324411 DOI: 10.1021/acs.nanolett.0c00504] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Heterostructures built from 2D, atomically thin crystals are bound by the van der Waals force and exhibit unique optoelectronic properties. Here, we report the structure, composition and optoelectronic properties of 1D van der Waals heterostructures comprising carbon nanotubes wrapped by atomically thin nanotubes of boron nitride and molybdenum disulfide (MoS2). The high quality of the composite was directly made evident on the atomic scale by transmission electron microscopy, and on the macroscopic scale by a study of the heterostructure's equilibrium and ultrafast optoelectronics. Ultrafast pump-probe spectroscopy across the visible and terahertz frequency ranges identified that, in the MoS2 nanotubes, excitons coexisted with a prominent population of free charges. The electron mobility was comparable to that found in high-quality atomically thin crystals. The high mobility of the MoS2 nanotubes highlights the potential of 1D van der Waals heterostructures for nanoscale optoelectronic devices.
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Affiliation(s)
- Maria G Burdanova
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Reza J Kashtiban
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Yongjia Zheng
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Rong Xiang
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Shohei Chiashi
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Jack Matthew Woolley
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Michael Staniforth
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Emily Sakamoto-Rablah
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Xue Xie
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Matthew Broome
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | - Jeremy Sloan
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | | | - Esko I Kauppinen
- Department of Applied Physics, Aalto University School of Science, Espoo 15100, Aalto FI-00076, Finland
| | - Shigeo Maruyama
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - James Lloyd-Hughes
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
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42
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Xu T, Wang H, Chen X, Luo M, Zhang L, Wang Y, Chen F, Shan C, Yu C. Recent progress on infrared photodetectors based on InAs and InAsSb nanowires. NANOTECHNOLOGY 2020; 31:294004. [PMID: 32235081 DOI: 10.1088/1361-6528/ab8591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In recent years, quasi-1D semiconductor nanowires have attracted significant research interest in the field of optoelectronic devices. Indium arsenide (InAs) nanowire, a III-V compound semiconductor structure with a narrow band gap, shows high electron mobility and high absorption from the visible to the mid-wave infrared (MWIR), holding promise for room-temperature high-performance infrared photodetectors. Therefore, the material growth, device preparation and performance characteristics have attracted increasing attention, enabling high-sensitivity InAs nanowire photodetector from the visible to the MWIR at room temperature. This review starts by discussing the growth process of the low-dimensional structure and elementary properties of the material, such as the crystalline phase, mobility, morphology, surface states and metal contacts. Then, three solutions, including the visible-light-assisted infrared photodetection technology, vertical nanowire-array technology and band engineering by the growth of InAsSb nanowires with increasing Sb components, are elaborated to obtain longer cut-off wavelength MWIR photodetectors based on single InAs nanowire and its heterojunction structure. Finally, the potential and challenges of the state-of-the-art optoelectronic technologies for InAs nanowire MWIR photodetectors are summarized and compared, and preliminary suggestions for the technical development route and prospects are presented. This review mainly delineates the research progress of material growth, device fabrication and performance characterization of InAs nanowire MWIR photodetectors, providing a reference for the development of the next-generation high-performance photodetectors over a wide spectrum range.
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Affiliation(s)
- Tengfei Xu
- Jiangsu Key Laboratory of ASIC Design, School of Information Science and Technology, Nantong University, Nantong 226019, People's Republic of China. Key Laboratory of Space Active Opto-Electronics Technology, and State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, People's Republic of China
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43
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Xing X, Zhao L, Zhang W, Wang Z, Su H, Chen H, Ma G, Dai J, Zhang W. Influence of a substrate on ultrafast interfacial charge transfer and dynamical interlayer excitons in monolayer WSe 2/graphene heterostructures. NANOSCALE 2020; 12:2498-2506. [PMID: 31930248 DOI: 10.1039/c9nr09309e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Efficient interfacial light-electric interconversion in van der Waals heterostructures is critical for their optoelectronic applications. Using time-resolved terahertz spectroscopy and transient absorption spectroscopy, the charge transfer and the dynamical interlayer excitons were investigated in the heterostructures comprising monolayer WSe2 and monolayer graphene with varying stacking order on a sapphire substrate. Herein, a more comprehensive understanding of ultrafast charge transfer and exciton dynamics in two-dimensional heterostructures is shown. Owing to the effective electric field induced by the sapphire substrate, the WSe2/graphene heterostructure exhibits positive terahertz photoconductivity after photoexcitation, while negative terahertz photoconductivity is observed in the graphene/WSe2 heterostructure. The transient absorption spectra indicate that the exciton lifetimes also exhibit a considerable difference, where WSe2/graphene exhibits the longest exciton lifetime, followed by monolayer WSe2, while graphene/WSe2 exhibits the shortest lifetime. These observations provide a new idea for using van der Waals heterostructures in electronic and photonic devices.
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Affiliation(s)
- Xiao Xing
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
| | - Litao Zhao
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
| | - Wenjie Zhang
- Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
| | - Zhuo Wang
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
| | - Huimin Su
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China.
| | - Huaying Chen
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, Shenzhen 518055, China
| | - Guohong Ma
- Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
| | - Junfeng Dai
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China.
| | - Wenjing Zhang
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
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44
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Liu X, Li Y, Guo W. Friction Modulation via Photoexcitation in Two-Dimensional Materials. ACS APPLIED MATERIALS & INTERFACES 2020; 12:2910-2915. [PMID: 31852182 DOI: 10.1021/acsami.9b20285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We demonstrate a photoexcitation-friction coupling in bilayered black phosphorus, a two-dimensional semiconductor crystallized via van der Waals interaction, using density functional theory and the Prandtl-Tomlinson model. Under an experimentally accessible electron-hole density of 5 × 1013 cm-2, the energy barrier for interlayer sliding can be reduced by 13% and the resultant reduction of critical force for stick-slip transition can be up to 4.7%. With the carrier density being doubled, the frictional anisotropy can even be eliminated. Analysis based on Born-Oppenheimer approximation shows that photoexcitation-friction coupling can be universal for van der Waals crystals with interlayer electronic states responsive to both photoexcitation and interlayer sliding.
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Affiliation(s)
- Xiaofei Liu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education , Nanjing University of Aeronautics and Astronautics , Nanjing 210016 , China
| | - Yao Li
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education , Nanjing University of Aeronautics and Astronautics , Nanjing 210016 , China
| | - Wanlin Guo
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education , Nanjing University of Aeronautics and Astronautics , Nanjing 210016 , China
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45
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Dal Conte S, Trovatello C, Gadermaier C, Cerullo G. Ultrafast Photophysics of 2D Semiconductors and Related Heterostructures. TRENDS IN CHEMISTRY 2020. [DOI: 10.1016/j.trechm.2019.07.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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46
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Ren Y, Ge Y, Wan W, Li Q, Liu Y. Two dimensional ferromagnetic semiconductor: monolayer CrGeS 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:015701. [PMID: 31509817 DOI: 10.1088/1361-648x/ab4395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Recently, two-dimensional ferromagnetic semiconductors have been an important class of materials for many potential applications in spintronic devices. Based on density functional theory, we systematically explore the magnetic and electronic properties of CrGeS3 with the monolayer structures. It is found that the bandgap of spin-up state is 1.01 eV when it is 1.07 eV in spin-down state. The exchange splitting is calculated as 0.67 eV (2.21 eV by HSE06 functional), which originates from bonding [Formula: see text] hybridized states of Cr e g -S p and unoccupied Cr t 2g -Ge p hybridization. After that, the comparison of total energy between different magnetic states ensures the ferromagnetic ground state of monolayer CrGeS3. The reason of the magnetic states originates mainly from the competition between antiferromagnetic direct neighboring Cr-Cr exchange and ferromagnetic superexchange mediated by S atom. And the results also show the magnetic moment of 6 [Formula: see text] per unit cell, including two Cr atoms. Besides, we estimate that the monolayer CrGeS3 possesses the Curie temperature of 161 K by mean-field theory. The results suggest that monolayer CrGeS3 crystals will possess potential applications in nanoscale spintronics.
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Affiliation(s)
- Yulu Ren
- State Key Laboratory of Metastable Materials Science and Technology & Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
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47
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Wen Y, He P, Wang Q, Yao Y, Zhang Y, Hussain S, Wang Z, Cheng R, Yin L, Getaye Sendeku M, Wang F, Jiang C, He J. Gapless van der Waals Heterostructures for Infrared Optoelectronic Devices. ACS NANO 2019; 13:14519-14528. [PMID: 31794184 DOI: 10.1021/acsnano.9b08375] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mixed-dimensional van der Waals (vdW) heterostructures based on two-dimensional (2D) materials exhibit immense potential in infrared optoelectronic applications. However, the weak vdW coupling results in limiting performance of infrared optoelectronic device. Here, we exploit a gapless heterostructure that S dangling bonds of nonlayered PbS are connected to the bonding sites of MoS2 (with factitious S vacancies) via strong orbital hybridization. The strong interface coupling leads to ultrahigh responsivity and photogain (G) exceeding 105, and the detectivity (D*) is greater than 1014 Jones. More importantly, the gapless heterostructure shows fast rise and decay times about 47 and 49 μs, respectively, which is 5 orders of magnitude faster than that of transferred vdW heterostructures. Furthermore, an ultrahigh photon-triggered on/off ratio of 1.6 × 106 is achieved, which is 4 orders of magnitude higher than that of transferred vdW heterostructures. This architecture can offer an effective approach for advanced infrared optoelectronic devices.
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Affiliation(s)
- Yao Wen
- School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Peng He
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Qisheng Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Yuyu Yao
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Yu Zhang
- School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Sabir Hussain
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Zhenxing Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Ruiqing Cheng
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Lei Yin
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Marshet Getaye Sendeku
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Feng Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Chao Jiang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Jun He
- School of Physics and Technology , Wuhan University , Wuhan 430072 , China
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48
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Lee H, Deshmukh S, Wen J, Costa VZ, Schuder JS, Sanchez M, Ichimura AS, Pop E, Wang B, Newaz AKM. Layer-Dependent Interfacial Transport and Optoelectrical Properties of MoS 2 on Ultraflat Metals. ACS APPLIED MATERIALS & INTERFACES 2019; 11:31543-31550. [PMID: 31364836 DOI: 10.1021/acsami.9b09868] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Layered materials based on transition-metal dichalcogenides (TMDs) are promising for a wide range of electronic and optoelectronic devices. Realizing such practical applications often requires metal-TMD connections or contacts. Hence, a complete understanding of electronic band alignments and potential barrier heights governing the transport through metal-TMD junctions is critical. However, it is presently unclear how the energy bands of a TMD align while in contact with a metal as a function of the number of layers. In pursuit of removing this knowledge gap, we have performed conductive atomic force microscopy (CAFM) of few-layered (1 to 5 layers) MoS2 immobilized on ultraflat conducting Au surfaces [root-mean-square (rms) surface roughness < 0.2 nm] and indium-tin oxide (ITO) substrates (rms surface roughness < 0.7 nm) forming a vertical metal (CAFM tip)-semiconductor-metal device. We have observed that the current increases with the number of layers up to five layers. By applying Fowler-Nordheim tunneling theory, we have determined the barrier heights for different layers and observed how this barrier decreases as the number of layers increases. Using density functional theory calculations, we successfully demonstrated that the barrier height decreases as the layer number increases. By illuminating TMDs on a transparent ultraflat conducting ITO substrate, we observed a reduction in current when compared to the current measured in the dark, hence demonstrating negative photoconductivity. Our study provides a fundamental understanding of the local electronic and optoelectronic behaviors of the TMD-metal junction, which depends on the numbers of TMD layers and may pave an avenue toward developing nanoscale electronic devices with tailored layer-dependent transport properties.
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Affiliation(s)
| | | | - Jing Wen
- School of Chemical, Biological and Materials Engineering , University of Oklahoma , Norman , Oklahoma 73019 , United States
- Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering , Harbin Normal University , Harbin 150025 , P. R. China
| | | | | | | | | | | | - Bin Wang
- School of Chemical, Biological and Materials Engineering , University of Oklahoma , Norman , Oklahoma 73019 , United States
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49
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Liu E, van Baren J, Lu Z, Altaiary MM, Taniguchi T, Watanabe K, Smirnov D, Lui CH. Gate Tunable Dark Trions in Monolayer WSe_{2}. PHYSICAL REVIEW LETTERS 2019; 123:027401. [PMID: 31386514 DOI: 10.1103/physrevlett.123.027401] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Indexed: 06/10/2023]
Abstract
Monolayer WSe_{2} is an intriguing material to explore dark exciton physics. We have measured the photoluminescence from dark excitons and trions in ultraclean monolayer WSe_{2} devices encapsulated by boron nitride. The dark trions can be tuned continuously between negative and positive trions with electrostatic gating. We reveal their spin-triplet configuration and distinct valley optical emission by their characteristic Zeeman splitting under a magnetic field. The dark trion binding energies are 14-16 meV, slightly lower than the bright trion binding energies (21-35 meV). The dark trion lifetime (∼1.3 ns) is two orders of magnitude longer than the bright trion lifetime (∼10 ps) and can be tuned between 0.4 and 1.3 ns by gating. Such robust, optically detectable, and gate tunable dark trions may help us realize trion transport in two-dimensional materials.
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Affiliation(s)
- Erfu Liu
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Jeremiah van Baren
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Zhengguang Lu
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
- Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
| | - Mashael M Altaiary
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Takashi Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - Chun Hung Lui
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
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50
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Xu S, Yang J, Jiang H, Su F, Zeng Z. Transient photoconductivity and free carrier dynamics in a monolayer WS 2 probed by time resolved Terahertz spectroscopy. NANOTECHNOLOGY 2019; 30:265706. [PMID: 30861497 DOI: 10.1088/1361-6528/ab0f02] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The frequency and time resolved conductivity in a photoexcited large-area monolayer tungsten disulfide (WS2) have been simultaneously determined by using time-resolved terahertz spectroscopy. We use the Drude-Smith model to successfully reproduce the transient photoconductivity spectra, which demonstrate that localized free carriers, not bounded excitons, are responsible for the THz transport. Upon the optical excitation with 400 nm and 530 nm wavelength, the relaxation dynamics of the free carriers include fast and slow decay components with time constants approximately smaller than 1 ps and between 5-7 ps, respectively. The former sub-picosecond decay is attributed to the charge carrier loss induced by the exciton formation, while both the Auger recombination and the surface trapping can contribute to the slow relaxation.
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Affiliation(s)
- Shujuan Xu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China. University of Science and Technology of China, Hefei 230026, People's Republic of China
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