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Ji Z, Song Y, Song Y, Li Z, Zhang J, Lou S, Zhang Z, Jin Q. Temperature-Dependent Spin-to-Charge Conversion and Efficient Manipulation of Elliptical THz Waves in Bi 2Te 3/TbFeCo Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38656108 DOI: 10.1021/acsami.4c02263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Topological insulators (TIs) with spin-momentum-locked surface states and considerable spin-to-charge conversion (SCC) efficiency are ideal substitutes for the nonmagnetic layer in the traditional ferromagnetic/nonmagnetic (FM/NM) spintronic terahertz (THz) emitters. Here, the TI/ferrimagnetic structure as an effective polarization tunable THz source is verified by terahertz emission spectroscopy. The emitted THz electric field can be separated into two THz components utilizing their opposite symmetry on pump polarization and the magnetic field. TI not only emits a THz electric field via the linear photogalvanic effect (LPGE) but also serves as the medium of SCC via the inverse Edelstein effect (IEE) in the heterostructure. In addition, the amplitude and polarity of the SCC component can be efficiently manipulated by temperature in our ferrimagnetic TbFeCo layer compared with Co or Fe. Once these two THz components are delicately set orthogonally, an elliptical THz wave is generated by the intrinsic phase difference at the THz frequency range. The feasible control of its polarization and chirality is demonstrated by three means: pump polarization, magnetic field, and temperature. These appealing observations may pave the way for the development of elliptical THz wave emitters and polarization-sensitive THz spectroscopy.
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Affiliation(s)
- Zhihao Ji
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Yuna Song
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Yiwen Song
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Ziyang Li
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Jingying Zhang
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Shitao Lou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Zongzhi Zhang
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| | - Qingyuan Jin
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Laboratory of Micro and Nano Photonic Structures (MOE), Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
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2
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Yang D, Laarman JH, Tonouchi M. Sensitive Characterization of the Graphene Transferred onto Varied Si Wafer Surfaces via Terahertz Emission Spectroscopy and Microscopy (TES/LTEM). MATERIALS (BASEL, SWITZERLAND) 2024; 17:1497. [PMID: 38612011 PMCID: PMC11012325 DOI: 10.3390/ma17071497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/23/2024] [Accepted: 03/24/2024] [Indexed: 04/14/2024]
Abstract
Graphene shows great potential in developing the next generation of electronic devices. However, the real implementation of graphene-based electronic devices needs to be compatible with existing silicon-based nanofabrication processes. Characterizing the properties of the graphene/silicon interface rapidly and non-invasively is crucial for this endeavor. In this study, we employ terahertz emission spectroscopy and microscopy (TES/LTEM) to evaluate large-scale chemical vapor deposition (CVD) monolayer graphene transferred onto silicon wafers, aiming to assess the dynamic electronic properties of graphene and perform large-scale graphene mapping. By comparing THz emission properties from monolayer graphene on different types of silicon substrates, including those treated with buffered oxide etches, we discern the influence of native oxide layers and surface dipoles on graphene. Finally, the mechanism of THz emission from the graphene/silicon heterojunction is discussed, and the large-scale mapping of monolayer graphene on silicon is achieved successfully. These results demonstrate the efficacy of TES/LTEM for graphene characterization in the modern graphene-based semiconductor industry.
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Affiliation(s)
- Dongxun Yang
- Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan
| | - Jesse Henri Laarman
- Department of Applied Physics, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
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3
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Zhou T, Li L, Wang Y, Zhao S, Liu M, Zhu J, Li W, Lin Z, Li J, Sun B, Huang Q, Zhang G, Zou C. Multifield-Modulated Spintronic Terahertz Emitter Based on a Vanadium Dioxide Phase Transition. ACS APPLIED MATERIALS & INTERFACES 2024; 16:13997-14005. [PMID: 38447142 DOI: 10.1021/acsami.3c19488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The efficient generation and active modulation of terahertz (THz) waves are strongly required for the development of various THz applications such as THz imaging/spectroscopy and THz communication. In addition, due to the increasing degree of integration for the THz optoelectronic devices, miniaturizing the complex THz system into a compact unit is also important and necessary. Today, integrating the THz source with the modulator to develop a powerful, easy-to-adjust, and scalable or on-chip THz emitter is still a challenge. As a new type of THz emitter, a spintronic THz emitter has attracted a great deal of attention due to its advantages of high efficiency, ultrawide band, low cost, and easy integration. In this study, we have proposed a multifield-modulated spintronic THz emitter based on the VO2/Ni/Pt multilayer film structure with a wide band region of 0-3 THz. Because of the pronounced phase transition of the integrated VO2 layer, the fabricated THz emitter can be efficiently modulated via thermal or electric stimuli with a modulation depth of about one order of magnitude; the modulation depths under thermal stimulation and electrical stimulation were 91.8% and 97.3%, respectively. It is believed that this multifield modulated spintronic THz emitter will provide various possibilities for the integration of next-generation on-chip THz sources and THz modulators.
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Affiliation(s)
- Ting Zhou
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Liang Li
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Yangkai Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Shanguang Zhao
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Meiling Liu
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Jinglin Zhu
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Weiwei Li
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Zhihan Lin
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Jianjun Li
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Bowen Sun
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Qiuping Huang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Guobin Zhang
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
- Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Chongwen Zou
- National Synchrotron Radiation Laboratory, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
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Balos V, Wolf M, Kovalev S, Sajadi M. Optical rectification and electro-optic sampling in quartz. OPTICS EXPRESS 2023; 31:13317-13327. [PMID: 37157471 DOI: 10.1364/oe.480339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We report the electro-optic sampling (EOS) response and the terahertz (THz) optical rectification (OR) of the z-cut α-quartz. Due to its small effective second-order nonlinearity, large transparency window and hardness, freestanding thin quartz plates can faithfully measure the waveform of intense THz pulses with MV/cm electric-field strength. We show that both its OR and EOS responses are broad with extension up to ∼8 THz. Strikingly, the latter responses are independent of the crystal thickness, a plausible indication of dominant surface contribution to the total second-order nonlinear susceptibility of quartz at THz frequencies. Our study introduces the crystalline quartz as a reliable THz electro-optic medium for high field THz detection, and characterize its emission as a common substrate.
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Real-time observation of the buildup of polaron in α-FAPbI 3. Nat Commun 2023; 14:917. [PMID: 36801865 PMCID: PMC9938110 DOI: 10.1038/s41467-023-36652-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 02/10/2023] [Indexed: 02/19/2023] Open
Abstract
The formation of polaron, i.e., the strong coupling process between the carrier and lattice, is considered to play a crucial role in benefiting the photoelectric performance of hybrid organic-inorganic halide perovskites. However, direct observation of the dynamical formation of polarons occurring at time scales within hundreds of femtoseconds remains a technical challenge. Here, by terahertz emission spectroscopy, we demonstrate the real-time observation of polaron formation process in FAPbI3 films. Two different polaron resonances interpreted with the anharmonic coupling emission model have been studied: P1 at ~1 THz relates to the inorganic sublattice vibration mode and the P2 at ~0.4 THz peak relates to the FA+ cation rotation mode. Moreover, P2 could be further strengthened than P1 by pumping the hot carriers to the higher sub-conduction band. Our observations could open a door for THz emission spectroscopy to be a powerful tool in studying polaron formation dynamics in perovskites.
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Cheng L, Xiong Y, Kang L, Gao Y, Chang Q, Chen M, Qi J, Yang H, Liu Z, Song JC, Chia EE. Giant photon momentum locked THz emission in a centrosymmetric Dirac semimetal. SCIENCE ADVANCES 2023; 9:eadd7856. [PMID: 36598995 PMCID: PMC9812375 DOI: 10.1126/sciadv.add7856] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Strong second-order optical nonlinearities often require broken material centrosymmetry, thereby limiting the type and quality of materials used for nonlinear optical devices. Here, we report a giant and highly tunable terahertz (THz) emission from thin polycrystalline films of the centrosymmetric Dirac semimetal PtSe2. Our PtSe2 THz emission is turned on at oblique incidence and locked to the photon momentum of the incident pump beam. Notably, we find an emitted THz efficiency that is giant: It is two orders of magnitude larger than the standard THz-generating nonlinear crystal ZnTe and has values approaching that of the noncentrosymmetric topological material TaAs. Further, PtSe2 THz emission displays THz sign and amplitude that is controlled by the incident pump polarization and helicity state even as optical absorption is only weakly polarization dependent and helicity independent. Our work demonstrates how photon drag can activate pronounced optical nonlinearities that are available even in centrosymmetric Dirac materials.
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Affiliation(s)
- Liang Cheng
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Ying Xiong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Lixing Kang
- Division of Advanced Materials, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Yu Gao
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Qing Chang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Mengji Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jingbo Qi
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 637371, Singapore
| | - Justin C.W. Song
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Elbert E. M. Chia
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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7
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Pan Z, Liu W, Yu L, Xie Z, Sun Q, Zhao P, Chen D, Fang W, Liu B. Resonance-Induced Reduction of Interfacial Tension of Water-Methane and Improvement of Methane Solubility in Water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:13594-13601. [PMID: 36299165 DOI: 10.1021/acs.langmuir.2c02392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Molecular dynamics simulations were performed to study the effect of the periodic oscillating electric field on the interface between water and methane. We propose a new strategy that utilizes oscillating electric fields to reduce the interfacial tension (IFT) between water and methane and increase the solubility of methane in water simultaneously. These are attributed to the hydrogen bond resonance induced by an electric field with a frequency close to the natural frequency of the hydrogen bond. The resonance breaks the hydrogen bond network among water molecules to the maximum, which destroys the hydration shell and reduces the cohesive action of water, thus resulting in the decrease of IFT and the increase of methane solubility. As the frequency of the electric field is close to the optimum resonant frequency of hydrogen bonds, IFT decreases from 56.43 to 5.66 mN/m; water and methane are miscible because the solubility parameter of water reduces from 47.63 to 2.85 MPa1/2, which is close to that of methane (3.43 MPa1/2). Our results provide a new idea for reducing the water-gas IFT and improving the solubility of insoluble gas in water and theoretical guidance in the fields of natural gas exploitation, hydrate generation, and nanobubble nucleation.
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Affiliation(s)
- Zhiming Pan
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Wenyu Liu
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Leyang Yu
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Zhiyang Xie
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Qing Sun
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Peihe Zhao
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Dongmeng Chen
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Wenjing Fang
- College of Science, China University of Petroleum (East China), Qingdao266580, China
| | - Bing Liu
- College of Science, China University of Petroleum (East China), Qingdao266580, China
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8
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Park H, Rho S, Kim J, Kim H, Kim D, Kang C, Cho M. Topological Surface-Dominated Spintronic THz Emission in Topologically Nontrivial Bi 1- x Sb x Films. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200948. [PMID: 35596613 PMCID: PMC9313944 DOI: 10.1002/advs.202200948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/12/2022] [Indexed: 05/13/2023]
Abstract
Topological materials have significant potential for spintronic applications owing to their superior spin-charge interconversion. Here, the spin-to-charge conversion (SCC) characteristics of epitaxial Bi1- x Sbx films is investigated across the topological phase transition by spintronic terahertz (THz) spectroscopy. An unexpected, intense spintronic THz emission is observed in the topologically nontrivial semimetal Bi1- x Sbx films, significantly greater than that of Pt and Bi2 Se3 , which indicates the potential of Bi1- x Sbx for spintronic applications. More importantly, the topological surface state (TSS) is observed to significantly contribute to SCC, despite the coexistence of the bulk state, which is possible via a unique ultrafast SCC process, considering the decay process of the spin-polarized hot electrons. This means that topological material-based spintronic devices should be fabricated in a manner that fully utilizes the TSS, not the bulk state, to maximize their performance. The results not only provide a clue for identifying the source of the giant spin Hall angle of Bi1- x Sbx , but also expand the application potential of topological materials by indicating that the optically induced spin current provides a unique method for focused-spin injection into the TSS.
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Affiliation(s)
- Hanbum Park
- Department of PhysicsYonsei UniversitySeoul03722Republic of Korea
- Department of Electrical and Computer EngineeringNational University of SingaporeSingapore119260Singapore
| | - Seungwon Rho
- Department of PhysicsYonsei UniversitySeoul03722Republic of Korea
| | - Jonghoon Kim
- Department of PhysicsYonsei UniversitySeoul03722Republic of Korea
| | - Hyeongmun Kim
- Department of PhysicsChonnam National UniversityGwangju61186Republic of Korea
- Advanced Photonics Research InstituteGwangju Institute of Science and TechnologyGwangju61005Republic of Korea
| | - Dajung Kim
- Department of PhysicsYonsei UniversitySeoul03722Republic of Korea
| | - Chul Kang
- Advanced Photonics Research InstituteGwangju Institute of Science and TechnologyGwangju61005Republic of Korea
| | - Mann‐Ho Cho
- Department of PhysicsYonsei UniversitySeoul03722Republic of Korea
- Department of System Semiconductor EngineeringYonsei UniversitySeoul03722Republic of Korea
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Shi Z, Zhang H, Khan K, Cao R, Zhang Y, Ma C, Tareen AK, Jiang Y, Jin M, Zhang H. Two-dimensional materials toward Terahertz optoelectronic device applications. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2022. [DOI: 10.1016/j.jphotochemrev.2021.100473] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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Xi F, Yang H, Khayrudinov V, He Y, Haggren T, Zhou Y, Lipsanen H, Sun Z, Xu X. Enhanced terahertz emission from mushroom-shaped InAs nanowire network induced by linear and nonlinear optical effects. NANOTECHNOLOGY 2021; 33:085207. [PMID: 34768252 DOI: 10.1088/1361-6528/ac3948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
The development of powerful terahertz (THz) emitters is the cornerstone for future THz applications, such as communication, medical biology, non-destructive inspection, and scientific research. Here, we report the THz emission properties and mechanisms of mushroom-shaped InAs nanowire (NW) network using linearly polarized laser excitation. By investigating the dependence of THz signal to the incidence pump light properties (e.g. incident angle, direction, fluence, and polarization angle), we conclude that the THz wave emission from the InAs NW network is induced by the combination of linear and nonlinear optical effects. The former is a transient photocurrent accelerated by the photo-Dember field, while the latter is related to the resonant optical rectification effect. Moreover, thep-polarized THz wave emission component is governed by the linear optical effect with a proportion of ∼85% and the nonlinear optical effect of ∼15%. In comparison, thes-polarized THz wave emission component is mainly decided by the nonlinear optical effect. The THz emission is speculated to be enhanced by the localized surface plasmon resonance absorption of the In droplets on top of the NWs. This work verifies the nonlinear optical mechanism in the THz generation of semiconductor NWs and provides an enlightening reference for the structural design of powerful and flexible THz surface and interface emitters in transmission geometry.
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Affiliation(s)
- Fugang Xi
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710127, People's Republic of China
| | - He Yang
- School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, People's Republic of China
- Department of Electronics and Nanoengineering, Aalto University, Espoo, PO Box 13500, FI-00076, Finland
| | - Vladislav Khayrudinov
- Department of Electronics and Nanoengineering, Aalto University, Espoo, PO Box 13500, FI-00076, Finland
| | - Yuhang He
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710127, People's Republic of China
| | - Tuomas Haggren
- Department of Electronics and Nanoengineering, Aalto University, Espoo, PO Box 13500, FI-00076, Finland
| | - Yixuan Zhou
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710127, People's Republic of China
| | - Harri Lipsanen
- Department of Electronics and Nanoengineering, Aalto University, Espoo, PO Box 13500, FI-00076, Finland
| | - Zhipei Sun
- Department of Electronics and Nanoengineering, Aalto University, Espoo, PO Box 13500, FI-00076, Finland
| | - Xinlong Xu
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710127, People's Republic of China
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Wang H, Chang J, Huang Y, Lei Z, Du W, Zhou Y, E Y, Xu X. Large In-Plane Anisotropic Terahertz Emission Induced by Asymmetric Polarization in Low-Symmetric PdSe 2. ACS APPLIED MATERIALS & INTERFACES 2021; 13:54543-54550. [PMID: 34734685 DOI: 10.1021/acsami.1c16197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Palladium diselenide (PdSe2) exhibits air stability, low symmetry, and high carrier mobility, resulting in unique in-plane anisotropy for polarized optoelectronic devices. However, the relationship of the symmetry and the terahertz (THz) radiation remains elusive yet significant for both the THz source in technology and nonlinear optical physics in science. Herein, we observed large in-plane anisotropic THz radiation from multilayer PdSe2 under femtosecond laser excitation. The THz emission demonstrates 2α dependence on the optical polarization angle from the resonant optical rectification combined with a background from the photocarrier acceleration under the surface depletion field. Interestingly, the in-plane THz emission along and perpendicular to the puckered direction demonstrates large anisotropy. Furthermore, the THz time-domain signals exhibit reversed polarities along the positive and negative puckered directions. This asymmetric polarization could relate to the bonding of Pd-Se, resulting in the unidirectional photon-induced current. Our results bridge the gap between the low-symmetry two-dimensional materials and the THz technology, which could promote the development of THz-polarized devices based on low-symmetry layered materials.
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Affiliation(s)
- He Wang
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
| | - Jiawei Chang
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
| | - Yuanyuan Huang
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
| | - Zhen Lei
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
| | - Wanyi Du
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
| | - Yixuan Zhou
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
| | - Yiwen E
- The Institute of Optics, University of Rochester, Rochester, New York 14627, United States
| | - Xinlong Xu
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710127, China
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12
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Chang J, Wang H, Lei Z, Du W, Huang Y, Zhou Y, Zhu L, Xu X. Coherent Elliptically Polarized Terahertz Wave Generation in WSe 2 by Linearly Polarized Femtosecond Laser Excitation. J Phys Chem Lett 2021; 12:10068-10078. [PMID: 34623821 DOI: 10.1021/acs.jpclett.1c02770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Coherent polarization control of terahertz (THz) wave radiation in both the time-domain and the frequency-domain is significant in information technology, material science, and spectroscopic analysis. Elliptically polarized THz radiation is generally limited to chiral materials induced by circularly polarized light excitation. Herein, we demonstrate the coherent elliptically polarized THz radiation from few-layer tungsten diselenide (WSe2) in both the time-domain and the frequency-domain under linearly polarized femtosecond laser excitation. This coherent elliptical THz radiation is mainly dominated by in-plane anisotropic shift current and out-of-plane drift current, which is verified by the THz radiation dependence on the pump laser polarization angles, incident angles, and sample azimuthal angles systematically. The ellipticity and major axis direction of the elliptical THz wave can be efficiently controlled by either pump light polarization or sample azimuthal angle due to the controllable amplitudes and phases of two coherent orthogonal THz wave components. Our finding provides a method to distinguish drift and shift photocurrents in different directions and offers a unique design concept for elliptical THz generation with two-dimensional (2D) material physics.
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Affiliation(s)
- Jiawei Chang
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
| | - He Wang
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
| | - Zhen Lei
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
| | - Wanyi Du
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
| | - Yuanyuan Huang
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
| | - Yixuan Zhou
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
| | - Lipeng Zhu
- School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, China
| | - Xinlong Xu
- Shaanxi Joint Lab of Graphene, State Key Laboratory of Photon-Technology in Western China Energy, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Xi'an 710069, China
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13
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Huang L, Zhang L, Zhou J, Li M, Li C, Li C, Zhang J, Wang S, Zeng H. Surface plasmon enhanced THz emission with nanoporous gold supported CdTe. OPTICS EXPRESS 2021; 29:19853-19861. [PMID: 34266087 DOI: 10.1364/oe.424230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 05/27/2021] [Indexed: 06/13/2023]
Abstract
Terahertz emission by ultrafast excitation of semiconductor/metal interfaces was found strongly enhanced by plasmon resonance. Here, a three-dimensional nanoporous gold (NPG) was used to form semiconductor/metal compound with cadmium telluride (CdTe). We investigated the specific impact of surface plasmon from randomly nanoporous structure in the ultrafast optoelectronic response for THz generation, and observed a THz amplitude enhancement around an order of magnitude from CdTe on NPG compared to that from CdTe on silicon. Moreover, the plasmon enhancement for THz emission from NPG is stronger than that from gold film, indicating that randomly nanoporous structure is also effective for plasmonic enhancement in THz band.
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14
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Fan Z, Xu M, Huang Y, Lei Z, Zheng L, Zhang Z, Zhao W, Zhou Y, Wang X, Xu X, Liu Z. Terahertz Surface Emission from MoSe 2 at the Monolayer Limit. ACS APPLIED MATERIALS & INTERFACES 2020; 12:48161-48169. [PMID: 32990422 DOI: 10.1021/acsami.0c13474] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The surface-charge region of bulk and monolayer MoSe2 is analyzed directly by terahertz (THz) surface emission spectroscopy in a nondestructive way. Both surface nonlinear optical polarization and surface field-induced photocurrent contribute to the THz radiation in both bulk and monolayer MoSe2. The first THz emission mechanism is due to the surface optical rectification and the second one is due to the photogenerated carriers accelerated by the surface depletion field. The THz radiation contribution from the surface optical rectification is basically the same for both bulk and monolayer MoSe2 because of the same symmetry at the surface. However, the contribution from the surface field-induced photocurrent is ∼94.2% in bulk MoSe2 and it goes down to 74.5% in monolayer MoSe2. This is due to the larger surface depletion field in bulk MoSe2 (∼2.54 × 107 V/m) compared with that in monolayer MoSe2 (∼5.42 × 105 V/m), as such THz emission from the bulk is approximately four times larger than that from monolayer MoSe2. This work not only proves the clear THz radiation mechanism from MoSe2 crystals but also affords a THz technology for the surface characterization of two-dimensional materials.
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Affiliation(s)
- Zeyu Fan
- Shaanxi Joint Lab of Graphene, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710069, China
| | - Manzhang Xu
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, Xi'an 710072, China
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Yuanyuan Huang
- Shaanxi Joint Lab of Graphene, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710069, China
| | - Zhen Lei
- Shaanxi Joint Lab of Graphene, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710069, China
| | - Lu Zheng
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, Xi'an 710072, China
| | - Zhiyong Zhang
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Wu Zhao
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yixuan Zhou
- Shaanxi Joint Lab of Graphene, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710069, China
| | - Xuewen Wang
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, Xi'an 710072, China
| | - Xinlong Xu
- Shaanxi Joint Lab of Graphene, Institute of Photonics & Photon-Technology, School of Physics, Northwest University, Xi'an 710069, China
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
- Centre for Micro-/Nano-Electronics (NOVITAS), School of Electrical & Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
- CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Singapore 637553, Singapore
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15
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Terahertz Emission Spectroscopy and Microscopy on Ultrawide Bandgap Semiconductor β-Ga2O3. PHOTONICS 2020. [DOI: 10.3390/photonics7030073] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although gallium oxide Ga2O3 is attracting much attention as a next-generation ultrawide bandgap semiconductor for various applications, it needs further optical characterization to support its use in higher-performance devices. In the present study, terahertz (THz) emission spectroscopy (TES) and laser THz emission microscopy (LTEM) are applied to Sn-doped, unintentionally doped, and Fe-doped β-Ga2O3 wafers. Femtosecond (fs) laser illumination generated THz waves based on the time derivative of the photocurrent. TES probes the motion of ultrafast photocarriers that are excited into a conduction band, and LTEM visualizes their local spatiotemporal movement at a spatial and temporal resolution of laser beam diameter and a few hundred fs. In contrast, one observes neither photoluminescence nor distinguishable optical absorption for a band-to-band transition for Ga2O3. TES/LTEM thus provides complementary information on, for example, the local mobility, surface potential, defects, band bending, and anisotropic photo-response in a noncontact, nondestructive manner. The results indicated that the band bends downward at the surface of an Fe-doped wafer, unlike with an n-type wafer, and the THz emission intensity is qualitatively proportional to the product of local electron mobility and diffusion potential, and is inversely proportional to penetration depth, all of which have a strong correlation with the quality of the materials and defects/impurities in them.
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16
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Ultrafast spatiotemporal photocarrier dynamics near GaN surfaces studied by terahertz emission spectroscopy. Sci Rep 2020; 10:14633. [PMID: 32884079 PMCID: PMC7471959 DOI: 10.1038/s41598-020-71728-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/14/2020] [Indexed: 11/24/2022] Open
Abstract
Gallium nitride (GaN) is a promising wide-bandgap semiconductor, and new characterization tools are needed to study its local crystallinity, carrier dynamics, and doping effects. Terahertz (THz) emission spectroscopy (TES) is an emerging experimental technique that can probe the ultrafast carrier dynamics in optically excited semiconductors. In this work, the carrier dynamics and THz emission mechanisms of GaN were examined in unintentionally doped n-type, Si-doped n-type, and Mg-doped p-type GaN films. The photocarriers excited near the surface travel from the excited-area in an ultrafast manner and generate THz radiation in accordance with the time derivative of the surge drift current. The polarity of the THz amplitude can be used to determine the majority carrier type in GaN films through a non-contact and non-destructive method. Unique THz emission excited by photon energies less than the bandgap was also observed in the p-type GaN film.
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He C, Zhao Q, Huang Y, Zhu L, Zhang S, Bai J, Xu X. Nonlinear Optical Response in Graphene/WX 2 (X = S, Se, and Te) van der Waals Heterostructures. J Phys Chem Lett 2019; 10:2090-2100. [PMID: 30973733 DOI: 10.1021/acs.jpclett.9b00217] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Light-frequency conversion based on two-dimensional (2D) materials is of great importance for modern nano- and integrated photonics. Herein, we report both the intrinsic (from the pure WX2 (X = S, Se, and Te)) and extrinsic (from the interface of graphene/WX2) second-order nonlinear coefficient tensor from graphene/WX2 van der Waals (vdW) heterostructures by first-principles calculations. The prominent peaks in the dispersion relation of the intrinsic second-order nonlinear coefficient in monolayer WX2 are due to the Van Hove singularity in the high-symmetry point or along the high-symmetry line with high joint density of states. The enhanced nonlinear optical response in the infrared band can be achieved in graphene/WS2 vdW heterostructures, resulting from the interlayer charge transfer between graphene and WS2. The value of the intrinsic second-order nonlinear coefficients of graphene/WSe2 vdW heterostructures is 1.5 times larger than that of pure monolayer WSe2 at the band gap energy of monolayer WSe2 because of the enhanced carrier generation after the heterostructure formation. Different from pure monolayer WX2, azimuthal angle-dependent second harmonic generation from graphene/WX2 vdW heterostructures exhibits extraordinary rotational symmetry at different photon energies, which can be used to deduce the extrinsic second-order nonlinear coefficient. These results pave the way for the nonlinear optical coefficient design based on 2D heterostructures for nonlinear nanophotonics and integrated devices.
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Affiliation(s)
- Chuan He
- Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology , Northwest University , Xi'an 710069 , China
| | - Qiyi Zhao
- School of Science , Xi'an University of Posts & Telecommunications , Xi'an 710121 , China
| | - Yuanyuan Huang
- Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology , Northwest University , Xi'an 710069 , China
| | - Lipeng Zhu
- School of Electronic Engineering , Xi'an University of Posts & Telecommunications , Xi'an 710121 , China
| | - Sujuan Zhang
- Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology , Northwest University , Xi'an 710069 , China
| | - Jintao Bai
- Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology , Northwest University , Xi'an 710069 , China
| | - Xinlong Xu
- Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology , Northwest University , Xi'an 710069 , China
- Guangxi Key Laboratory of Automatic Detecting Technology and Instruments , Guilin University of Electronic Technology , Guilin 541004 , China
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