1
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Ulibarri AC, Lew CTK, Lim SQ, McCallum JC, Johnson BC, Harmand JC, Peretti J, Rowe ACH. Deep-Level Structure of the Spin-Active Recombination Center in Dilute Nitrides. PHYSICAL REVIEW LETTERS 2024; 132:186402. [PMID: 38759200 DOI: 10.1103/physrevlett.132.186402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 04/15/2024] [Indexed: 05/19/2024]
Abstract
A gallium interstitial defect is thought to be responsible for the spectacular spin-dependent recombination in GaAs_{1-x}N_{x} dilute nitrides. Current understanding associates this defect with at least two in-gap levels corresponding to the (+/0) and (++/+) charge-state transitions. Using a spin-sensitive photoinduced current transient spectroscopy, the in-gap electronic structure of a x=0.021 alloy is revealed. The (+/0) state lies ≈0.27 eV below the conduction band edge, and an anomalous, negative activation energy reveals the presence of not one but two other in-gap states. The observations are consistent with a (++/+) state ≈0.19 eV above the valence band edge, and a (+++/++) state ≈25 meV above the valence band edge.
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Affiliation(s)
- A C Ulibarri
- Laboratoire de physique de la matière condensée, CNRS, Ecole Polytechnique, IP Paris, 91128 Palaiseau, France
| | - C T K Lew
- Centre of Excellence for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - S Q Lim
- Centre of Excellence for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - J C McCallum
- School of Physics, University of Melbourne, Parkville, VIC, Australia
| | - B C Johnson
- School of Science, RMIT University, Melbourne 3001, Australia
| | - J C Harmand
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, 91120 Palaiseau, France
| | - J Peretti
- Laboratoire de physique de la matière condensée, CNRS, Ecole Polytechnique, IP Paris, 91128 Palaiseau, France
| | - A C H Rowe
- Laboratoire de physique de la matière condensée, CNRS, Ecole Polytechnique, IP Paris, 91128 Palaiseau, France
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2
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Park S, Hiura S, Kise H, Takayama J, Sueoka K, Murayama A. Room-temperature electric field control of spin filtering efficiency for enhanced modulation of optical spin polarization in a defect-functional 0D-2D hybrid nanostructure. NANOSCALE 2023; 15:16784-16794. [PMID: 37819237 DOI: 10.1039/d3nr03438k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
In order to accomplish spin-based photoelectric information processing, it is necessary to modulate electron spin polarization in III-V semiconductor quantum dots (QDs) using an electric field. However, there is a principal limitation to the spin polarization degree and its control range, as the electron spin polarization is rapidly lost during injection into the QDs at room temperature (RT). Here, electric field control of optical spin polarization in the range of 15-40% is demonstrated at RT using InAs QDs tunnel-coupled with a defect-functional GaNAs quantum well (QW) spin filter. This compares with an electric field control of 1-4% for InAs QDs tunnel-coupled with an InGaAs QW. Transient polarization in the range of 30-60% is also obtained in the ultrafast time domain of less than 100 ps, the degree of polarization depending on the electric field. The enhanced polarization control is achieved by tuning the amplified spin polarization of electrons tunnel-injected from the GaNAs QW into QDs via the electric-field-dependent spin-filtering efficiency of GaNAs. These findings will provide a new way to extensively modulate the electron spin polarization in opto-semiconductors, by electric-field-induced on/off switching of spin amplification.
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Affiliation(s)
- Soyoung Park
- Faculty of Information Science and Technology, Hokkaido University, 060-0814, Japan.
| | - Satoshi Hiura
- Faculty of Information Science and Technology, Hokkaido University, 060-0814, Japan.
| | - Hiroto Kise
- Faculty of Information Science and Technology, Hokkaido University, 060-0814, Japan.
| | - Junichi Takayama
- Faculty of Information Science and Technology, Hokkaido University, 060-0814, Japan.
| | - Kazuhisa Sueoka
- Faculty of Information Science and Technology, Hokkaido University, 060-0814, Japan.
| | - Akihiro Murayama
- Faculty of Information Science and Technology, Hokkaido University, 060-0814, Japan.
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3
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Ponce-Pérez R, Guerrero-Sanchez J, Hoat DM. Half-metallic and magnetic semiconductor behavior in CdO monolayer induced by acceptor impurities. Phys Chem Chem Phys 2023; 25:14266-14273. [PMID: 37171208 DOI: 10.1039/d3cp01268a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In this work, a doping approach is explored as a possible method to induce novel features in the CdO monolayer for spintronic applications. Monolayer CdO is a two-dimensional (2D) non-magnetic semiconductor material with a band gap of 0.82 eV. In monolayer CdO, a single Cd vacancy leads to magnetization of the monolayer with a total magnetic moment of -2μB, whereas its non-magnetic nature is preserved upon creating a single O vacancy. Doping the Cd sublattice with Cu-Ag and Au induces half-metallic character with a total magnetic moment of -1 and 1μB, respectively. Dopants and their neighboring O atoms produce mainly magnetic properties. By contrast, doping with N, P, and As at the O sublattice leads to the emergence of magnetic semiconductor behavior with a total magnetic moment of 1μB. Herein, magnetism originates mainly from the spin-asymmetric charge distribution in the outermost orbitals of the dopants. Bader charge analysis and charge density difference calculations indicate charge transfer from Cu, Ag and Au dopants to the host monolayer, whereas the N, P and As dopants exhibit important charge gains. These results suggest that doping with acceptor impurities is an efficient approach to functionalize the CdO monolayer to generate spin currents in spintronic devices.
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Affiliation(s)
- R Ponce-Pérez
- Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Apartado Postal 14, Ensenada, Baja California, Código Postal 22800, Mexico
| | - J Guerrero-Sanchez
- Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Apartado Postal 14, Ensenada, Baja California, Código Postal 22800, Mexico
| | - D M Hoat
- Institute of Theoretical and Applied Research, Duy Tan University, Ha Noi 100000, Vietnam.
- Faculty of Natural Sciences, Duy Tan University, Da Nang 550000, Vietnam
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4
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Ni PN, Fu P, Chen PP, Xu C, Xie YY, Genevet P. Spin-decoupling of vertical cavity surface-emitting lasers with complete phase modulation using on-chip integrated Jones matrix metasurfaces. Nat Commun 2022; 13:7795. [PMID: 36528625 PMCID: PMC9759547 DOI: 10.1038/s41467-022-34977-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 11/14/2022] [Indexed: 12/23/2022] Open
Abstract
Polarization response of artificially structured nano-antennas can be exploited to design innovative optical components, also dubbed "vectorial metasurfaces", for the modulation of phase, amplitude, and polarization with subwavelength spatial resolution. Recent efforts in conceiving Jones matrix formalism led to the advancement of vectorial metasurfaces to independently manipulate any arbitrary phase function of orthogonal polarization states. Here, we are taking advantages of this formalism to design and experimentally validate the performance of CMOS compatible Jones matrix metasurfaces monolithically integrated with standard VCSELs for on-chip spin-decoupling and phase shaping. Our approach enables accessing the optical spin states of VCSELs in an ultra-compact way with previously unattainable phase controllability. By exploiting spin states as a new degree of freedom for laser wavefront engineering, our platform is capable of operating and reading-out the spin-momentum of lasers associated with injected spin carriers, which would potentially play a pivotal role for the development of emerging spin-optoelectronic devices.
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Affiliation(s)
- Pei-Nan Ni
- grid.450300.2Université Côte d’Azur, CNRS, Centre de Recherche sur l’Hétéro-Epitaxie et ses Applications (CRHEA), Valbonne, France
| | - Pan Fu
- grid.28703.3e0000 0000 9040 3743Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing, China
| | - Pei-Pei Chen
- grid.419265.d0000 0004 1806 6075Nanofabrication Laboratory, CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Beijing, China
| | - Chen Xu
- grid.28703.3e0000 0000 9040 3743Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing, China
| | - Yi-Yang Xie
- grid.28703.3e0000 0000 9040 3743Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing, China
| | - Patrice Genevet
- grid.450300.2Université Côte d’Azur, CNRS, Centre de Recherche sur l’Hétéro-Epitaxie et ses Applications (CRHEA), Valbonne, France
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5
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Balagula RM, Jansson M, Yukimune M, Stehr JE, Ishikawa F, Chen WM, Buyanova IA. Effects of thermal annealing on localization and strain in core/multishell GaAs/GaNAs/GaAs nanowires. Sci Rep 2020; 10:8216. [PMID: 32427905 PMCID: PMC7237432 DOI: 10.1038/s41598-020-64958-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 04/27/2020] [Indexed: 11/10/2022] Open
Abstract
Core/shell nanowire (NW) heterostructures based on III-V semiconductors and related alloys are attractive for optoelectronic and photonic applications owing to the ability to modify their electronic structure via bandgap and strain engineering. Post-growth thermal annealing of such NWs is often involved during device fabrication and can also be used to improve their optical and transport properties. However, effects of such annealing on alloy disorder and strain in core/shell NWs are not fully understood. In this work we investigate these effects in novel core/shell/shell GaAs/GaNAs/GaAs NWs grown by molecular beam epitaxy on (111) Si substrates. By employing polarization-resolved photoluminescence measurements, we show that annealing (i) improves overall alloy uniformity due to suppressed long-range fluctuations in the N composition; (ii) reduces local strain within N clusters acting as quantum dot emitters; and (iii) leads to partial relaxation of the global strain caused by the lattice mismatch between GaNAs and GaAs. Our results, therefore, underline applicability of such treatment for improving optical quality of NWs from highly-mismatched alloys. They also call for caution when using ex-situ annealing in strain-engineered NW heterostructures.
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Affiliation(s)
- Roman M Balagula
- Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
| | - Mattias Jansson
- Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden.
| | - Mitsuki Yukimune
- Graduate School of Science and Engineering, Ehime University, 790-8577, Matsuyama, Japan
| | - Jan E Stehr
- Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
| | - Fumitaro Ishikawa
- Graduate School of Science and Engineering, Ehime University, 790-8577, Matsuyama, Japan
| | - Weimin M Chen
- Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
| | - Irina A Buyanova
- Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
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6
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Jansson M, Francaviglia L, La R, Balagula R, Stehr JE, Tu CW, Fontcuberta I Morral A, Chen WM, Buyanova IA. Increasing N content in GaNAsP nanowires suppresses the impact of polytypism on luminescence. NANOTECHNOLOGY 2019; 30:405703. [PMID: 31242464 DOI: 10.1088/1361-6528/ab2cdb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cathodoluminescence (CL) and micro-photoluminescence spectroscopies are employed to investigate effects of structural defects on carrier recombination in GaNAsP nanowires (NWs) grown by molecular beam epitaxy on Si substrates. In the NWs with a low N content of 0.08%, these defects are found to promote non-radiative (NR) recombination, which causes spatial variation of the CL peak position and its intensity. Unexpectedly, these detrimental effects can be suppressed even by a small increase in the nitrogen composition from 0.08% to 0.12%. This is attributed to more efficient trapping of excited carriers/excitons to the localized states promoted by N-induced localization and also the presence of other NR channels. At room temperature, the structural defects no longer dominate in carrier recombination even in the NWs with the lower nitrogen content, likely due to increasing importance of other recombination channels. Our work underlines the need in eliminating important thermally activated NR defects, other than the structural defects, for future optoelectronic applications of these NWs.
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Affiliation(s)
- Mattias Jansson
- Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden
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7
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Anders J, Lips K. MR to go. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 306:118-123. [PMID: 31327536 DOI: 10.1016/j.jmr.2019.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/02/2019] [Accepted: 07/08/2019] [Indexed: 05/03/2023]
Abstract
In this paper, we provide a review of the recent advances in miniaturizing nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectrometers for portable magnetic resonance (MR) applications. We focus the discussion on the application of integrated circuit technology for the miniaturization of the NMR and EPR spectrometer hardware and/or the detector and we will briefly touch on magnet technology. Finally, we will summarize current challenges of chip-integrated spectrometers and give an outlook on future applications of mobile MR spectrometers.
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Affiliation(s)
- J Anders
- University of Stuttgart, Institute of Smart Sensors and IQ(ST) (Center for Integrated Quantum Science and Technology), Stuttgart, Germany.
| | - K Lips
- Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin Joint EPR Lab, Institute Nanospectroscopy, Berlin, Germany.
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8
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Buyanova IA, Chen WM. Dilute nitrides-based nanowires-a promising platform for nanoscale photonics and energy technology. NANOTECHNOLOGY 2019; 30:292002. [PMID: 30933933 DOI: 10.1088/1361-6528/ab1516] [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
Dilute nitrides are novel III-V-N semiconductor alloys promising for a great variety of applications ranging from nanoscale light emitters and solar cells to energy production via photoelectrochemical reactions and to nano-spintronics. These alloys have become available in the one-dimensional geometry only most recently, thanks to the advances in the nanowire (NW) growth utilizing molecular beam epitaxy. In this review we will summarize growth approaches currently utilized for the fabrication of such novel dilute nitride-based NWs, discuss their structural, defect-related and optical properties, as well as provide several examples of their potential applications.
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9
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Chen S, Yukimune M, Fujiwara R, Ishikawa F, Chen WM, Buyanova IA. Near-Infrared Lasing at 1 μm from a Dilute-Nitride-Based Multishell Nanowire. NANO LETTERS 2019; 19:885-890. [PMID: 30608174 DOI: 10.1021/acs.nanolett.8b04103] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A coherent photon source emitting at near-infrared (NIR) wavelengths is at the heart of a wide variety of applications ranging from telecommunications and optical gas sensing to biological imaging and metrology. NIR-emitting semiconductor nanowires (NWs), acting both as a miniaturized optical resonator and as a photonic gain medium, are among the best-suited nanomaterials to achieve such goals. In this study, we demonstrate the NIR lasing at 1 μm from GaAs/GaNAs/GaAs core/shell/cap dilute nitride nanowires with only 2.5% nitrogen. The achieved lasing is characterized by an S-shape pump-power dependence and narrowing of the emission line width. Through examining the lasing performance from a set of different single NWs, a threshold gain, gth, of 4100-4800 cm-1, was derived with a spontaneous emission coupling factor, β, up to 0.8, which demonstrates the great potential of such nanophotonic material. The lasing mode was found to arise from the fundamental HE11a mode of the Fabry-Perot cavity from a single NW, exhibiting optical polarization along the NW axis. Based on temperature dependence of the lasing emission, a high characteristic temperature, T0, of 160 (±10) K is estimated. Our results, therefore, demonstrate a promising alternative route to achieve room-temperature NIR NW lasers thanks to the excellent alloy tunability and superior optical performance of such dilute nitride materials.
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Affiliation(s)
- Shula Chen
- Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
| | - Mitsuki Yukimune
- Graduate School of Science and Engineering , Ehime University , Matsuyama 790-8577 , Japan
| | - Ryo Fujiwara
- Graduate School of Science and Engineering , Ehime University , Matsuyama 790-8577 , Japan
| | - Fumitaro Ishikawa
- Graduate School of Science and Engineering , Ehime University , Matsuyama 790-8577 , Japan
| | - Weimin M Chen
- Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
| | - Irina A Buyanova
- Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
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10
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Chen S, Huang Y, Visser D, Anand S, Buyanova IA, Chen WM. Room-temperature polarized spin-photon interface based on a semiconductor nanodisk-in-nanopillar structure driven by few defects. Nat Commun 2018; 9:3575. [PMID: 30177701 PMCID: PMC6120900 DOI: 10.1038/s41467-018-06035-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 08/13/2018] [Indexed: 11/24/2022] Open
Abstract
Owing to their superior optical properties, semiconductor nanopillars/nanowires in one-dimensional (1D) geometry are building blocks for nano-photonics. They also hold potential for efficient polarized spin-light conversion in future spin nano-photonics. Unfortunately, spin generation in 1D systems so far remains inefficient at room temperature. Here we propose an approach that can significantly enhance the radiative efficiency of the electrons with the desired spin while suppressing that with the unwanted spin, which simultaneously ensures strong spin and light polarization. We demonstrate high optical polarization of 20%, inferring high electron spin polarization up to 60% at room temperature in a 1D system based on a GaNAs nanodisk-in-GaAs nanopillar structure, facilitated by spin-dependent recombination via merely 2–3 defects in each nanodisk. Our approach points to a promising direction for realization of an interface for efficient spin-photon quantum information transfer at room temperature—a key element for future spin-photonic applications. Room-temperature spin-generation in 1D systems like semiconductor nanopillars is typically inefficient. Here, the authors demonstrate an approach to achieve efficient spin polarization, even in the absence of a magnetic field, by selectively enhancing the radiative efficiency of one spin direction.
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Affiliation(s)
- Shula Chen
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden.
| | - Yuqing Huang
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden
| | - Dennis Visser
- Department of Applied Physics, KTH Royal Institute of Technology, SE16440, Kista, Stockholm, Sweden
| | - Srinivasan Anand
- Department of Applied Physics, KTH Royal Institute of Technology, SE16440, Kista, Stockholm, Sweden
| | - Irina A Buyanova
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden
| | - Weimin M Chen
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden.
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11
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Ishikawa F, Higashi K, Fuyuno S, Morifuji M, Kondow M, Trampert A. Annealing induced atomic rearrangements on (Ga,In) (N,As) probed by hard X-ray photoelectron spectroscopy and X-ray absorption fine structure. Sci Rep 2018; 8:5962. [PMID: 29654243 PMCID: PMC5899128 DOI: 10.1038/s41598-018-23941-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/23/2018] [Indexed: 11/24/2022] Open
Abstract
We study the effects of annealing on (Ga0.64,In0.36) (N0.045,As0.955) using hard X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements. We observed surface oxidation and termination of the N-As bond defects caused by the annealing process. Specifically, we observed a characteristic chemical shift towards lower binding energies in the photoelectron spectra related to In. This phenomenon appears to be caused by the atomic arrangement, which produces increased In-N bond configurations within the matrix, as indicated by the X-ray absorption fine structure measurements. The reduction in the binding energies of group-III In, which occurs concomitantly with the atomic rearrangements of the matrix, causes the differences in the electronic properties of the system before and after annealing.
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Affiliation(s)
- Fumitaro Ishikawa
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan.
| | - Kotaro Higashi
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Innovation Research Center for Fuel Cells, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8285, Japan
| | - Satoshi Fuyuno
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Masato Morifuji
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Masahiko Kondow
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Achim Trampert
- Paul-Drude-Institute für Festköperelektronik, Hausvogteiplatz 5-7, 10117, Berlin, Germany
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12
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Liu M, Shi J, Li Y, Zhou X, Ma D, Qi Y, Zhang Y, Liu Z. Temperature-Triggered Sulfur Vacancy Evolution in Monolayer MoS 2 /Graphene Heterostructures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1602967. [PMID: 28799711 DOI: 10.1002/smll.201602967] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 07/05/2017] [Indexed: 06/07/2023]
Abstract
The existence of defects in 2D semiconductors has been predicted to generate unique physical properties and markedly influence their electronic and optoelectronic properties. In this work, it is found that the monolayer MoS2 prepared by chemical vapor deposition is nearly defect-free after annealing under ultrahigh vacuum conditions at ≈400 K, as evidenced by scanning tunneling microscopy observations. However, after thermal annealing process at ≈900 K, the existence of dominant single sulfur vacancies and relatively rare vacancy chains (2S, 3S, and 4S) is convinced in monolayer MoS2 as-grown on Au foils. Of particular significance is the revelation that the versatile vacancies can modulate the band structure of the monolayer MoS2 , leading to a decrease of the bandgap and an obvious n-doping effect. These results are confirmed by scanning tunneling spectroscopy data as well as first-principles theoretical simulations of the related morphologies and the electronic properties of the various defect types. Briefly, this work should pave a novel route for defect engineering and hence the electronic property modulation of three-atom-thin 2D layered semiconductors.
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Affiliation(s)
- Mengxi Liu
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Jianping Shi
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China
| | - Yuanchang Li
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Xiebo Zhou
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China
| | - Donglin Ma
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Yue Qi
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Yanfeng Zhang
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China
| | - Zhongfan Liu
- Center for Nanochemistry (CNC), Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
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13
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Filippov S, Jansson M, Stehr JE, Palisaitis J, Persson POÅ, Ishikawa F, Chen WM, Buyanova IA. Strongly polarized quantum-dot-like light emitters embedded in GaAs/GaNAs core/shell nanowires. NANOSCALE 2016; 8:15939-15947. [PMID: 27537077 DOI: 10.1039/c6nr05168e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent developments in fabrication techniques and extensive investigations of the physical properties of III-V semiconductor nanowires (NWs), such as GaAs NWs, have demonstrated their potential for a multitude of advanced electronic and photonics applications. Alloying of GaAs with nitrogen can further enhance the performance and extend the device functionality via intentional defects and heterostructure engineering in GaNAs and GaAs/GaNAs coaxial NWs. In this work, it is shown that incorporation of nitrogen in GaAs NWs leads to formation of three-dimensional confining potentials caused by short-range fluctuations in the nitrogen composition, which are superimposed on long-range alloy disorder. The resulting localized states exhibit a quantum-dot like electronic structure, forming optically active states in the GaNAs shell. By directly correlating the structural and optical properties of individual NWs, it is also shown that formation of the localized states is efficient in pure zinc-blende wires and is further facilitated by structural polymorphism. The light emission from these localized states is found to be spectrally narrow (∼50-130 μeV) and is highly polarized (up to 100%) with the preferable polarization direction orthogonal to the NW axis, suggesting a preferential orientation of the localization potential. These properties of self-assembled nano-emitters embedded in the GaNAs-based nanowire structures may be attractive for potential optoelectronic applications.
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Affiliation(s)
- S Filippov
- Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden.
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Ghosh S, Ghosh M, Seibt M, Rao GM. Detection of quantum well induced single degenerate-transition-dipoles in ZnO nanorods. NANOSCALE 2016; 8:2632-2638. [PMID: 26691877 DOI: 10.1039/c5nr06722g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Quantifying and characterising atomic defects in nanocrystals is difficult and low-throughput using the existing methods such as high resolution transmission electron microscopy (HRTEM). In this article, using a defocused wide-field optical imaging technique, we demonstrate that a single ultrahigh-piezoelectric ZnO nanorod contains a single defect site. We model the observed dipole-emission patterns from optical imaging with a multi-dimensional dipole and find that the experimentally observed dipole pattern and model-calculated patterns are in excellent agreement. This agreement suggests the presence of vertically oriented degenerate-transition-dipoles in vertically aligned ZnO nanorods. The HRTEM of the ZnO nanorod shows the presence of a stacking fault, which generates a localised quantum well induced degenerate-transition-dipole. Finally, we elucidate that defocused wide-field imaging can be widely used to characterise defects in nanomaterials to answer many difficult questions concerning the performance of low-dimensional devices, such as in energy harvesting, advanced metal-oxide-semiconductor storage, and nanoelectromechanical and nanophotonic devices.
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Affiliation(s)
- Siddharth Ghosh
- III. Institute of Physics, Georg-August-Universität-Göttingen, Friedrich-Hund-Platz 1, 37075 Göttingen, Germany.
| | - Moumita Ghosh
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India. and Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
| | - Michael Seibt
- IV. Institute of Physics, Georg-August-Universität-Göttingen, Freidrich-Hund-Platz 1, 37075 Göttingen, Germany
| | - G Mohan Rao
- Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
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15
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Kapitonov YV, Shapochkin PY, Beliaev LY, Petrov YV, Efimov YP, Eliseev SA, Lovtcius VA, Petrov VV, Ovsyankin VV. Ion-beam-assisted spatial modulation of inhomogeneous broadening of a quantum well resonance: excitonic diffraction grating. OPTICS LETTERS 2016; 41:104-6. [PMID: 26696169 DOI: 10.1364/ol.41.000104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We propose a method of spatial modulation of inhomogeneous broadening of a quantum-well excitonic resonance based on local generation of defects produced by a focused ion beam. The method is applied to fabrication of excitonic diffraction grating in a single quantum-well InGaAs/GaAs structure by irradiating the sample with a beam of 35-keV He+ ions of exposure doses <1012 cm-2. The spectrum of resonant diffraction on such a structure is narrower than that of reflectivity and decreases much faster with increasing temperature. A proposed model of formation of the diffractive response based on the single scattering approximation well describes the results of the spectral and temperature measurements.
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16
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Chen SL, Chen WM, Ishikawa F, Buyanova IA. Suppression of non-radiative surface recombination by N incorporation in GaAs/GaNAs core/shell nanowires. Sci Rep 2015; 5:11653. [PMID: 26100755 PMCID: PMC4477342 DOI: 10.1038/srep11653] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/05/2015] [Indexed: 11/15/2022] Open
Abstract
III-V semiconductor nanowires (NWs) such as GaAs NWs form an interesting artificial materials system promising for applications in advanced optoelectronic and photonic devices, thanks to the advantages offered by the 1D architecture and the possibility to combine it with the main-stream silicon technology. Alloying of GaAs with nitrogen can further enhance performance and extend device functionality via band-structure and lattice engineering. However, due to a large surface-to-volume ratio, III-V NWs suffer from severe non-radiative carrier recombination at/near NWs surfaces that significantly degrades optical quality. Here we show that increasing nitrogen composition in novel GaAs/GaNAs core/shell NWs can strongly suppress the detrimental surface recombination. This conclusion is based on our experimental finding that lifetimes of photo-generated free excitons and free carriers increase with increasing N composition, as revealed from our time-resolved photoluminescence (PL) studies. This is accompanied by a sizable enhancement in the PL intensity of the GaAs/GaNAs core/shell NWs at room temperature. The observed N-induced suppression of the surface recombination is concluded to be a result of an N-induced modification of the surface states that are responsible for the nonradiative recombination. Our results, therefore, demonstrate the great potential of incorporating GaNAs in III-V NWs to achieve efficient nano-scale light emitters.
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Affiliation(s)
- Shula L Chen
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden
| | - Weimin M Chen
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden
| | - Fumitaro Ishikawa
- Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan
| | - Irina A Buyanova
- Department of Physics, Chemistry and Biology, Linköping University, 58183, Linköping, Sweden
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17
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Rondin L, Tetienne JP, Hingant T, Roch JF, Maletinsky P, Jacques V. Magnetometry with nitrogen-vacancy defects in diamond. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:056503. [PMID: 24801494 DOI: 10.1088/0034-4885/77/5/056503] [Citation(s) in RCA: 278] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The isolated electronic spin system of the nitrogen-vacancy (NV) centre in diamond offers unique possibilities to be employed as a nanoscale sensor for detection and imaging of weak magnetic fields. Magnetic imaging with nanometric resolution and field detection capabilities in the nanotesla range are enabled by the atomic-size and exceptionally long spin-coherence times of this naturally occurring defect. The exciting perspectives that ensue from these characteristics have triggered vivid experimental activities in the emerging field of 'NV magnetometry'. It is the purpose of this article to review the recent progress in high-sensitivity nanoscale NV magnetometry, generate an overview of the most pertinent results of the last years and highlight perspectives for future developments. We will present the physical principles that allow for magnetic field detection with NV centres and discuss first applications of NV magnetometers that have been demonstrated in the context of nano magnetism, mesoscopic physics and the life sciences.
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Affiliation(s)
- L Rondin
- Laboratoire de Photonique Quantique et Moléculaire, Ecole Normale Supérieure de Cachan and CNRS UMR 8537, 94235 Cachan Cedex, France
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18
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Wang G, Liu BL, Balocchi A, Renucci P, Zhu CR, Amand T, Fontaine C, Marie X. Gate control of the electron spin-diffusion length in semiconductor quantum wells. Nat Commun 2014; 4:2372. [PMID: 24052071 PMCID: PMC3791469 DOI: 10.1038/ncomms3372] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 07/29/2013] [Indexed: 11/10/2022] Open
Abstract
The spin diffusion length is a key parameter to describe the transport properties of spin polarized electrons in solids. Electrical spin injection in semiconductor structures, a major issue in spintronics, critically depends on this spin diffusion length. Gate control of the spin diffusion length could be of great importance for the operation of devices based on the electric field manipulation and transport of electron spin. Here we demonstrate that the spin diffusion length in a GaAs quantum well can be electrically controlled. Through the measurement of the spin diffusion coefficient by spin grating spectroscopy and of the spin relaxation time by time-resolved optical orientation experiments, we show that the diffusion length can be increased by more than 200% with an applied gate voltage of 5 V. These experiments allow at the same time the direct simultaneous measurements of both the Rashba and Dresselhaus spin-orbit splittings.
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Affiliation(s)
- G Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100190, China
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19
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Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor. Nat Commun 2013; 4:1751. [PMID: 23612292 DOI: 10.1038/ncomms2776] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/21/2013] [Indexed: 11/08/2022] Open
Abstract
Nuclear spin hyperpolarization is essential to future solid-state quantum computation using nuclear spin qubits and in highly sensitive magnetic resonance imaging. Though efficient dynamic nuclear polarization in semiconductors has been demonstrated at low temperatures for decades, its realization at room temperature is largely lacking. Here we demonstrate that a combined effect of efficient spin-dependent recombination and hyperfine coupling can facilitate strong dynamic nuclear polarization of a defect atom in a semiconductor at room temperature. We provide direct evidence that a sizeable nuclear field (~150 Gauss) and nuclear spin polarization (~15%) sensed by conduction electrons in GaNAs originates from dynamic nuclear polarization of a Ga interstitial defect. We further show that the dynamic nuclear polarization process is remarkably fast and is completed in <5 μs at room temperature. The proposed new concept could pave a way to overcome a major obstacle in achieving strong dynamic nuclear polarization at room temperature, desirable for practical device applications.
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Puttisong Y, Buyanova IA, Ptak AJ, Tu CW, Geelhaar L, Riechert H, Chen WM. Room-temperature electron spin amplifier based on Ga(In)NAs alloys. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:738-742. [PMID: 23108727 DOI: 10.1002/adma.201202597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Indexed: 06/01/2023]
Abstract
The first experimental demonstration of a spin amplifier at room temperature is presented. An efficient, defect-enabled spin amplifier based on a non-magnetic semiconductor, Ga(In)NAs, is proposed and demonstrated, with a large spin gain (up to 2700% at zero field) for conduction electrons and a high cut-off frequency of up to 1 GHz.
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Phase composition and magnetic properties of niobium–iron codoped TiO2 nanoparticles synthesized in Ar/O2 radio-frequency thermal plasma. J SOLID STATE CHEM 2011. [DOI: 10.1016/j.jssc.2011.07.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Ivchenko EL, Kalevich VK, Shiryaev AY, Afanasiev MM, Masumoto Y. Optical orientation and spin-dependent recombination in GaAsN alloys under continuous-wave pumping. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:465804. [PMID: 21403378 DOI: 10.1088/0953-8984/22/46/465804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present a systematic theoretical study of spin-dependent recombination and its effect on optical orientation of photoelectron spins in semiconductors with deep paramagnetic centers. For this aim we generalize the Shockley-Read theory of recombination of electrons and holes through the deep centers with allowance for optically-induced spin polarization of free and bound electrons. Starting from consideration of defects with three charge states we turn to the two-charge-state model possessing nine parameters and show that it is compatible with available experimental data on undoped GaAsN alloys. In the weak- and strong-pumping limits, we derive simple analytic equations which are useful in prediction and interpretation of experimental results. Experimental and theoretical dependences of the spin-dependent recombination ratio and degree of photoluminescence circular polarization on the pumping intensity and the transverse magnetic field are compared and discussed.
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Affiliation(s)
- E L Ivchenko
- A F Ioffe Physico-Technical Institute, St Petersburg, Russia
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