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Al-Abri R, Al Amairi N, Church S, Byrne C, Sivakumar S, Walton A, Magnusson MH, Parkinson P. Sub-Picosecond Carrier Dynamics Explored using Automated High-Throughput Studies of Doping Inhomogeneity within a Bayesian Framework. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300053. [PMID: 37093214 DOI: 10.1002/smll.202300053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/27/2023] [Indexed: 05/03/2023]
Abstract
Bottom-up production of semiconductor nanomaterials is often accompanied by inhomogeneity resulting in a spread in electronic properties which may be influenced by the nanoparticle geometry, crystal quality, stoichiometry, or doping. Using photoluminescence spectroscopy of a population of more than 11 000 individual zinc-doped gallium arsenide nanowires, inhomogeneity is revealed in, and correlation between doping and nanowire diameter by use of a Bayesian statistical approach. Recombination of hot-carriers is shown to be responsible for the photoluminescence lineshape; by exploiting lifetime variation across the population, hot-carrier dynamics is revealed at the sub-picosecond timescale showing interband electronic dynamics. High-throughput spectroscopy together with a Bayesian approach are shown to provide unique insight in an inhomogeneous nanomaterial population, and can reveal electronic dynamics otherwise requiring complex pump-probe experiments in highly non-equilibrium conditions.
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Affiliation(s)
- Ruqaiya Al-Abri
- Department of Physics and Astronomy and the Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Nawal Al Amairi
- Department of Physics and Astronomy and the Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Stephen Church
- Department of Physics and Astronomy and the Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Conor Byrne
- Department of Chemistry and the Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Sudhakar Sivakumar
- Department of Physics and NanoLund, Lund University, Box 118, Lund, SE-221 00, Sweden
| | - Alex Walton
- Department of Chemistry and the Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Martin H Magnusson
- Department of Physics and NanoLund, Lund University, Box 118, Lund, SE-221 00, Sweden
| | - Patrick Parkinson
- Department of Physics and Astronomy and the Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
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Al-Abri R, Choi H, Parkinson P. Measuring, controlling and exploiting heterogeneity in optoelectronic nanowires. JPHYS PHOTONICS 2021. [DOI: 10.1088/2515-7647/abe282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Abstract
Fabricated from ZnO, III-N, chalcogenide-based, III-V, hybrid perovskite or other materials, semiconductor nanowires offer single-element and array functionality as photovoltaic, non-linear, electroluminescent and lasing components. In many applications their advantageous properties emerge from their geometry; a high surface-to-volume ratio for facile access to carriers, wavelength-scale dimensions for waveguiding or a small nanowire-substrate footprint enabling heterogeneous growth. However, inhomogeneity during bottom-up growth is ubiquitous and can impact morphology, geometry, crystal structure, defect density, heterostructure dimensions and ultimately functional performance. In this topical review, we discuss the origin and impact of heterogeneity within and between optoelectronic nanowires, and introduce methods to assess, optimise and ultimately exploit wire-to-wire disorder.
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3
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Skalsky S, Zhang Y, Alanis JA, Fonseka HA, Sanchez AM, Liu H, Parkinson P. Heterostructure and Q-factor engineering for low-threshold and persistent nanowire lasing. LIGHT, SCIENCE & APPLICATIONS 2020; 9:43. [PMID: 32194957 PMCID: PMC7078256 DOI: 10.1038/s41377-020-0279-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 02/10/2020] [Accepted: 03/02/2020] [Indexed: 05/28/2023]
Abstract
Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q-factor and population inversion conditions. We apply time-gated optical interferometry to the lasing emission from high-quality GaAsP/GaAs quantum well nanowire laser structures, revealing high Q-factors of 1250 ± 90 corresponding to end-facet reflectivities of R = 0.73 ± 0.02. By using optimised direct-indirect band alignment in the active region, we demonstrate a well-refilling mechanism providing a quasi-four-level system leading to multi-nanosecond lasing and record low room temperature lasing thresholds (~6 μJ cm-2 pulse-1) for III-V nanowire lasers. Our findings demonstrate a highly promising new route towards continuously operating silicon-integrated nanolaser elements.
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Affiliation(s)
- Stefan Skalsky
- Department of Physics and Astronomy and The Photon Science Institute, The University of Manchester, Manchester, M13 9PL UK
| | - Yunyan Zhang
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE UK
| | - Juan Arturo Alanis
- Department of Physics and Astronomy and The Photon Science Institute, The University of Manchester, Manchester, M13 9PL UK
| | - H. Aruni Fonseka
- Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Ana M. Sanchez
- Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Huiyun Liu
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE UK
| | - Patrick Parkinson
- Department of Physics and Astronomy and The Photon Science Institute, The University of Manchester, Manchester, M13 9PL UK
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4
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Himwas C, Collin S, Chen HL, Patriarche G, Oehler F, Travers L, Saket O, Julien FH, Harmand JC, Tchernycheva M. Correlated optical and structural analyses of individual GaAsP/GaP core-shell nanowires. NANOTECHNOLOGY 2019; 30:304001. [PMID: 30965307 DOI: 10.1088/1361-6528/ab1760] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report on the structural and optical properties of GaAs0.7P0.3/GaP core-shell nanowires (NWs) for future photovoltaic applications. The NWs are grown by self-catalyzed molecular beam epitaxy. Scanning transmission electron microscopy (STEM) analyses demonstrate that the GaAsP NW core develops an inverse-tapered shape with a formation of an unintentional GaAsP shell having a lower P content. Without surface passivation, this unintentional shell produces no luminescence because of strong surface recombination. However, passivation of the surface with a GaP shell leads to the appearance of a secondary peak in the luminescence spectrum arising from this unintentional shell. The attribution of the luminescence peaks is confirmed by correlated cathodoluminescence and STEM analyses of the same NW.
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Affiliation(s)
- C Himwas
- Centre de Nanosciences et de Nanotechnologies, UMR 9001 CNRS, Univ. Paris Sud, Univ. Paris-Saclay, 10 Boulevard Thomas Gobert, F-91120 Palaiseau Cedex, France. Semiconductor Device Research Laboratory, Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand
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Valente J, Godde T, Zhang Y, Mowbray DJ, Liu H. Light-Emitting GaAs Nanowires on a Flexible Substrate. NANO LETTERS 2018; 18:4206-4213. [PMID: 29894627 DOI: 10.1021/acs.nanolett.8b01100] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Semiconductor nanowire-based devices are among the most promising structures used to meet the current challenges of electronics, optics and photonics. Due to their high surface-to-volume ratio and excellent optical and electrical properties, devices with low power, high efficiency and high density can be created. This is of major importance for environmental issues and economic impact. Semiconductor nanowires have been used to fabricate high performance devices, including detectors, solar cells and transistors. Here, we demonstrate a technique for transferring large-area nanowire arrays to flexible substrates while retaining their excellent quantum efficiency in emission. Starting with a defect-free self-catalyzed molecular beam epitaxy (MBE) sample grown on a Si substrate, GaAs core-shell nanowires are embedded in a dielectric, removed by reactive ion etching and transferred to a plastic substrate. The original structural and optical properties, including the vertical orientation, of the nanowires are retained in the final plastic substrate structure. Nanowire emission is observed for all stages of the fabrication process, with a higher emission intensity observed for the final transferred structure, consistent with a reduction in nonradiative recombination via the modification of surface states. This transfer process could form the first critical step in the development of flexible nanowire-based light-emitting devices.
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Affiliation(s)
- João Valente
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Tillmann Godde
- Department of Physics and Astronomy , University of Sheffield , Sheffield S3 7RH , United Kingdom
| | - Yunyan Zhang
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - David J Mowbray
- Department of Physics and Astronomy , University of Sheffield , Sheffield S3 7RH , United Kingdom
| | - Huiyun Liu
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
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Himwas C, Collin S, Rale P, Chauvin N, Patriarche G, Oehler F, Julien FH, Travers L, Harmand JC, Tchernycheva M. In situ passivation of GaAsP nanowires. NANOTECHNOLOGY 2017; 28:495707. [PMID: 29057754 DOI: 10.1088/1361-6528/aa9533] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the structural and optical properties of GaAsP nanowires (NWs) grown by molecular-beam epitaxy. By adjusting the alloy composition in the NWs, the transition energy was tuned to the optimal value required for tandem III-V/silicon solar cells. We discovered that an unintentional shell was also formed during the GaAsP NW growth. The NW surface was passivated by an in situ deposition of a radial Ga(As)P shell. Different shell compositions and thicknesses were investigated. We demonstrate that the optimal passivation conditions for GaAsP NWs (with a gap of 1.78 eV) are obtained with a 5 nm thick GaP shell. This passivation enhances the luminescence intensity of the NWs by 2 orders of magnitude and yields a longer luminescence decay. The luminescence dynamics changes from single exponential decay with a 4 ps characteristic time in non-passivated NWs to a bi-exponential decay with characteristic times of 85 and 540 ps in NWs with GaP shell passivation.
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Affiliation(s)
- C Himwas
- Centre de Nanosciences et de Nanotechnologies-site Orsay, UMR 9001 CNRS, Univ. Paris Sud, Univ. Paris-Saclay, Bât 220, rue André Ampère, F-91405 Orsay, France
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7
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Dastjerdi MHT, Boulanger JP, Kuyanov P, Aagesen M, LaPierre RR. Methods of Ga droplet consumption for improved GaAs nanowire solar cell efficiency. NANOTECHNOLOGY 2016; 27:475403. [PMID: 27782007 DOI: 10.1088/0957-4484/27/47/475403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We describe methods of Ga droplet consumption in Ga-assisted GaAs nanowires, and their impact on the crystal structure at the tip of nanowires. Droplets are consumed under different group V flux conditions and the resulting tip crystal structure is examined by transmission electron microscopy. The use of GaAsP marker layers provides insight into the behavior of the Ga droplet during different droplet consumption conditions. Lower group V droplet supersaturations lead to a pure zincblende stacking-fault-free tip crystal structure, which improved the performance of a nanowire-based photovoltaic device.
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Affiliation(s)
- M H T Dastjerdi
- Department of Engineering Physics, Centre for Emerging Device Technologies, McMaster University, Hamilton, ON, L8S 4L7, Canada
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8
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Wu J, Ramsay A, Sanchez A, Zhang Y, Kim D, Brossard F, Hu X, Benamara M, Ware ME, Mazur YI, Salamo GJ, Aagesen M, Wang Z, Liu H. Defect-Free Self-Catalyzed GaAs/GaAsP Nanowire Quantum Dots Grown on Silicon Substrate. NANO LETTERS 2016; 16:504-511. [PMID: 26666697 DOI: 10.1021/acs.nanolett.5b04142] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The III-V nanowire quantum dots (NWQDs) monolithically grown on silicon substrates, combining the advantages of both one- and zero-dimensional materials, represent one of the most promising technologies for integrating advanced III-V photonic technologies on a silicon microelectronics platform. However, there are great challenges in the fabrication of high-quality III-V NWQDs by a bottom-up approach, that is, growth by the vapor-liquid-solid method, because of the potential contamination caused by external metal catalysts and the various types of interfacial defects introduced by self-catalyzed growth. Here, we report the defect-free self-catalyzed III-V NWQDs, GaAs quantum dots in GaAsP nanowires, on a silicon substrate with pure zinc blende structure for the first time. Well-resolved excitonic emission is observed with a narrow line width. These results pave the way toward on-chip III-V quantum information and photonic devices on silicon platform.
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Affiliation(s)
- Jiang Wu
- Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom
| | - Andrew Ramsay
- Hitachi Cambridge Laboratory, Hitachi Europe Ltd. , Cambridge CB3 0HE, United Kingdom
| | - Ana Sanchez
- Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Yunyan Zhang
- Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom
| | - Dongyoung Kim
- Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom
| | - Frederic Brossard
- Hitachi Cambridge Laboratory, Hitachi Europe Ltd. , Cambridge CB3 0HE, United Kingdom
| | - Xian Hu
- Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Mourad Benamara
- Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Morgan E Ware
- Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Yuriy I Mazur
- Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Gregory J Salamo
- Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Martin Aagesen
- Gasp Solar ApS , Gregersensvej 7, Taastrup DK-2630, Denmark
| | - Zhiming Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China , Chengdu 610054, People's Republic of China
| | - Huiyun Liu
- Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom
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9
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Jones EJ, Ermez S, Gradečak S. Mapping of Strain Fields in GaAs/GaAsP Core-Shell Nanowires with Nanometer Resolution. NANO LETTERS 2015; 15:7873-7879. [PMID: 26517289 DOI: 10.1021/acs.nanolett.5b02733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the nanoscale quantification of strain in GaAs/GaAsP core-shell nanowires. By tracking the shifting of higher-order Laue zone (HOLZ) lines in convergent beam electron diffraction patterns, we observe unique variations in HOLZ line separation along different facets of the core-shell structure, demonstrating the nonuniform strain fields created by the heterointerface. Furthermore, through the use of continuum mechanical modeling and Bloch wave analysis we calculate expected HOLZ line shift behavior, which are directly matched to experimental results. This comparison demonstrates both the power of electron microscopy as a platform for nanoscale strain characterization and the reliability of continuum models to accurately calculate complex strain fields in nanoscale systems.
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Affiliation(s)
- Eric J Jones
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Sema Ermez
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Silvija Gradečak
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Zhang Y, Sanchez AM, Wu J, Aagesen M, Holm JV, Beanland R, Ward T, Liu H. Polarity-Driven Quasi-3-Fold Composition Symmetry of Self-Catalyzed III-V-V Ternary Core-Shell Nanowires. NANO LETTERS 2015; 15:3128-3133. [PMID: 25822399 DOI: 10.1021/acs.nanolett.5b00188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A quasi-3-fold composition symmetry has for the first time been observed in self-catalyzed III-V-V core-shell nanowires. In GaAsP nanowires, phosphorus-rich sheets on radial {110} planes originating at the corners of the hexagonal core were observed. In a cross section, they appear as six radial P-rich bands that originate at the six outer corners of the hexagonal core, with three of them higher in P content along ⟨112⟩A direction and others along ⟨112⟩B, forming a quasi-3-fold composition symmetry. We propose that these P-rich bands are caused by a curvature-induced high surface chemical potential at the small corner facets, which drives As adatoms away more efficiently than P adatoms. Moreover, their polarity related P content difference can be explained by the different adatom bonding energies at these polar corner facets. These results provide important information on the further development of shell growth in the self-catalyzed core-shell NW structure and, hence, device structure for multicomponent material systems.
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Affiliation(s)
- Yunyan Zhang
- †Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
| | - Ana M Sanchez
- ‡Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Jiang Wu
- †Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
| | - Martin Aagesen
- §Gasp Solar ApS, Gregersensvej 7, Taastrup DK-2630, Denmark
| | - Jeppe V Holm
- §Gasp Solar ApS, Gregersensvej 7, Taastrup DK-2630, Denmark
- ∥Center for Quantum Devices, Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Richard Beanland
- ‡Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Thomas Ward
- ‡Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Huiyun Liu
- †Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom
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Im HS, Park K, Jang DM, Jung CS, Park J, Yoo SJ, Kim JG. Zn₃P₂-Zn₃As₂ solid solution nanowires. NANO LETTERS 2015; 15:990-7. [PMID: 25602167 DOI: 10.1021/nl5037897] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Semiconductor alloy nanowires (NWs) have recently attracted considerable attention for applications in optoelectronic nanodevices because of many notable properties, including band gap tunability. Zinc phosphide (Zn3P2) and zinc arsenide (Zn3As2) belong to a unique pseudocubic tetragonal system, but their solid solution has rarely been studied. Here In this study, we synthesized composition-tuned Zn3(P1-xAsx)2 NWs with different crystal structures by controlling the growth conditions during chemical vapor deposition. A first type of synthesized NWs were single-crystalline and grew uniformly along the [110] direction (in a cubic unit cell) over the entire compositional range (0 ≤ x ≤ 1) explored. The use of an indium source enabled the growth of a second type of NWs, with remarkable cubic-hexagonal polytypic twinned superlattice and bicrystalline structures. The growth direction of the Zn3P2 and Zn3As2 NWs was also switched to [111] and [112], respectively. These structural changes are attributable to the Zn-depleted indium catalytic nanoparticles which favor the growth of hexagonal phases. The formation of a solid solution at all compositions allowed the continuous tuning of the band gap (1.0-1.5 eV). Photocurrent measurements were performed on individual NWs by fabricating photodetector devices; the single-crystalline NWs with [110] growth direction exhibit a higher photoconversion efficiency compared to the twinned crystalline NWs with [111] or [112] growth direction.
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Affiliation(s)
- Hyung Soon Im
- Department of Chemistry, Korea University , Jochiwon 339-700, Korea
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12
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Park K, Lee JA, Im HS, Jung CS, Kim HS, Park J, Lee CL. GaP-ZnS pseudobinary alloy nanowires. NANO LETTERS 2014; 14:5912-5919. [PMID: 25234711 DOI: 10.1021/nl5028843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Multicomponent nanowires (NWs) are of great interest for integrated nanoscale optoelectronic devices owing to their widely tunable band gaps. In this study, we synthesize a series of (GaP)(1-x)(ZnS)(x) (0 ≤ x ≤ 1) pseudobinary alloy NWs using the vapor transport method. Compositional tuning results in the phase evolution from the zinc blende (ZB) (x < 0.4) to the wurtzite (WZ) phase (x > 0.7). A coexistence of ZB and WZ phases (x = 0.4-0.7) is also observed. In the intermediate phase coexistence range, a core-shell structure is produced with a composition of x = 0.4 and 0.7 for the core and shell, respectively. The band gap (2.4-3.7 eV) increases nonlinearly with increasing x, showing a significant bowing phenomenon. The phase evolution leads to enhanced photoluminescence emission. Strikingly, the photoluminescence spectrum shows a blue-shift (70 meV for x = 0.9) with increasing excitation power, and a wavelength-dependent decay time. Based on the photoluminescence data, we propose a type-II pseudobinary heterojunction band structure for the single-crystalline WZ phase ZnS-rich NWs. The slight incorporation of GaP into the ZnS induces a higher photocurrent and excellent photocurrent stability, which opens up a new strategy for enhancing the performance of photodetectors.
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Affiliation(s)
- Kidong Park
- Department of Chemistry, Korea University , Jochiwon 339-700, Korea
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Wang K, Rai SC, Marmon J, Chen J, Yao K, Wozny S, Cao B, Yan Y, Zhang Y, Zhou W. Nearly lattice matched all wurtzite CdSe/ZnTe type II core-shell nanowires with epitaxial interfaces for photovoltaics. NANOSCALE 2014; 6:3679-3685. [PMID: 24567192 DOI: 10.1039/c3nr06137j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Achieving a high-quality interface is of great importance in core-shell nanowire solar cells, as it significantly inhibits interfacial recombination and thus improves the photovoltaic performance. Combining thermal evaporation of CdSe and pulsed laser deposition of ZnTe, we successfully synthesized nearly lattice matched all wurtzite CdSe/ZnTe core-shell nanowires on silicon substrates. Comprehensive morphological and structural characterizations revealed that a wurtzite ZnTe shell layer epitaxially grows over a wurtzite CdSe core nanowire with an abrupt interface. Further optical studies confirmed a high-quality interface and demonstrated efficient charge separation induced by the type-II band alignment. A representative photovoltaic device has been demonstrated and yielded an energy-conversion efficiency of 1.7% which can be further improved by surface passivation. The all-wurtzite core-shell nanowire with an epitaxial interface offers an attractive platform to explore the piezo-phototronic effect and promises an efficient hybrid nano-sized, energy harvesting system.
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Affiliation(s)
- Kai Wang
- Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148, USA.
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Zhang Y, Aagesen M, Holm JV, Jørgensen HI, Wu J, Liu H. Self-catalyzed GaAsP nanowires grown on silicon substrates by solid-source molecular beam epitaxy. NANO LETTERS 2013; 13:3897-902. [PMID: 23899047 DOI: 10.1021/nl401981u] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We realize the growth of self-catalyzed GaAsP nanowires (NWs) on silicon (111) substrates using solid-source molecular beam epitaxy. By optimizing the V/III and P/As flux ratios, as well as the Ga flux, high-crystal-quality GaAsP NWs have been demonstrated with almost pure zinc-blende phase. Comparing the growth of GaAsP NWs with that of the conventional GaAs NWs indicates that the incorporation of P has significant effects on catalyst nucleation energy, and hence the nanowire morphology and crystal quality. In addition, the incorporation ratio of P/As between vapor-liquid-solid NW growth and the vapor-solid thin film growth has been compared, and the difference between these two growth modes is explained through growth kinetics. The vapor-solid epitaxial growth of radial GaAsP shell on core GaAsP NWs is further demonstrated with room-temperature emission at ~710 nm. These results give valuable new information into the NW nucleation mechanisms and open up new perspectives for integrating III-V nanowire photovoltaics and visible light emitters on a silicon platform by using self-catalyzed GaAsP core-shell nanowires.
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Affiliation(s)
- Yunyan Zhang
- Department of Electronic and Electrical Engineering, University College London, London, United Kingdom.
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