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Zeng L, Olsson E. Unveiling Variations in Electronic and Atomic Structures Due to Nanoscale Wurtzite and Zinc Blende Phase Separation in GaAs Nanowires. NANO LETTERS 2024. [PMID: 38767455 DOI: 10.1021/acs.nanolett.4c01262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Phase separation is an intriguing phenomenon often found in III-V nanostructures, but its effect on the atomic and electronic structures of III-V nanomaterials is still not fully understood. Here we study the variations in atomic arrangement and band structure due to the coexistence of wurtzite (WZ) and zinc blende (ZB) phases in single GaAs nanowires by using scanning transmission electron microscopy and monochromated electron energy loss spectroscopy. The WZ lattice distances are found to be larger (by ∼1%), along both the nanowire length direction and the perpendicular direction, than the ZB lattice. The band gap of the WZ phase is ∼20 meV smaller than that of the ZB phase. A shift of ∼70 meV in the conduction band edge between the two phases is also found. The direct and local measurements in single GaAs nanowires reveal important effects of phase separation on the properties of individual III-V nanostructures.
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Affiliation(s)
- Lunjie Zeng
- Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Eva Olsson
- Department of Physics, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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Schmiedeke P, Panciera F, Harmand JC, Travers L, Koblmüller G. Real-time thermal decomposition kinetics of GaAs nanowires and their crystal polytypes on the atomic scale. NANOSCALE ADVANCES 2023; 5:2994-3004. [PMID: 37260482 PMCID: PMC10228496 DOI: 10.1039/d3na00135k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 05/02/2023] [Indexed: 06/02/2023]
Abstract
Nanowires (NWs) offer unique opportunities for tuning the properties of III-V semiconductors by simultaneously controlling their nanoscale dimensions and switching their crystal phase between zinc-blende (ZB) and wurtzite (WZ). While much of this control has been enabled by direct, forward growth, the reverse reaction, i.e., crystal decomposition, provides very powerful means to further tailor properties towards the ultra-scaled dimensional level. Here, we use in situ transmission electron microscopy (TEM) to investigate the thermal decomposition kinetics of clean, ultrathin GaAs NWs and the role of distinctly different crystal polytypes in real-time and on the atomic scale. The whole process, from the NW growth to the decomposition, is conducted in situ without breaking vacuum to maintain pristine crystal surfaces. Radial decomposition occurs much faster for ZB- compared to WZ-phase NWs, due to the development of nano-faceted sidewall morphology and sublimation along the entire NW length. In contrast, WZ NWs form single-faceted, vertical sidewalls with decomposition proceeding only via step-flow mechanism from the NW tip. Concurrent axial decomposition is generally faster than the radial process, but is significantly faster (∼4-fold) in WZ phase, due to the absence of well-defined facets at the tip of WZ NWs. The results further show quantitatively the influence of the NW diameter on the sublimation and step-flow decomposition velocities elucidating several effects that can be exploited to fine-tune the NW dimensions.
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Affiliation(s)
- Paul Schmiedeke
- Technical University of Munich, Walter Schottky Institute, TUM School of Natural Sciences, Physics Department Garching 85747 Germany
| | - Federico Panciera
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Saclay 10 Boulevard Thomas Gobert 91120 Palaiseau France
| | - Jean-Christophe Harmand
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Saclay 10 Boulevard Thomas Gobert 91120 Palaiseau France
| | - Laurent Travers
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Saclay 10 Boulevard Thomas Gobert 91120 Palaiseau France
| | - Gregor Koblmüller
- Technical University of Munich, Walter Schottky Institute, TUM School of Natural Sciences, Physics Department Garching 85747 Germany
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Becdelievre J, Guan X, Dudko I, Regreny P, Chauvin N, Patriarche G, Gendry M, Danescu A, Penuelas J. Growing self-assisted GaAs nanowires up to 80 μm long by molecular beam epitaxy. NANOTECHNOLOGY 2022; 34:045603. [PMID: 36270200 DOI: 10.1088/1361-6528/ac9c6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Ultralong GaAs nanowires were grown by molecular beam epitaxy using the vapor-liquid-solid method. In this ultralong regime we show the existence of two features concerning the growth kinetic and the structural properties. Firstly, we observed a non-classical growth mode, where the axial growth rate is attenuated. Secondly, we observed structural defects at the surface of Wurtzite segments located at the bottom part of the nanowires. We explain these two phenomena as arising from a particular pathway of the group V species, specific to ultralong nanowires. Finally, the optical properties of such ultralong nanowires are studied by photoluminescence experiments.
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Affiliation(s)
- Jeanne Becdelievre
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
| | - Xin Guan
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
| | - I Dudko
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
- School of Engineering, RMIT University, Melbourne 3001, Victoria, Australia
- Functional Materials and Microsystems, Research Group and Micro Nano Research Facility, RMIT University, Melbourne 3001, Victoria, Australia
| | - Philippe Regreny
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
| | - Nicolas Chauvin
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
| | - Gilles Patriarche
- Centre de Nanosciences et de Nanotechnologies-C2N, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91120 Palaiseau, France
| | - Michel Gendry
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
| | - Alexandre Danescu
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
| | - José Penuelas
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon, CPE Lyon, INL, UMR5270, F69130 Ecully, France
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Dursap T, Vettori M, Botella C, Regreny P, Blanchard N, Gendry M, Chauvin N, Bugnet M, Danescu A, Penuelas J. Wurtzite phase control for self-assisted GaAs nanowires grown by molecular beam epitaxy. NANOTECHNOLOGY 2021; 32:155602. [PMID: 33429384 DOI: 10.1088/1361-6528/abda75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The accurate control of the crystal phase in III-V semiconductor nanowires (NWs) is an important milestone for device applications. Although cubic zinc-blende (ZB) GaAs is a well-established material in microelectronics, the controlled growth of hexagonal wurtzite (WZ) GaAs has thus far not been achieved successfully. Specifically, the prospect of growing defect-free and gold catalyst-free wurtzite GaAs would pave the way towards integration on silicon substrate and new device applications. In this article, we present a method to select and maintain the WZ crystal phase in self-assisted NWs by molecular beam epitaxy. By choosing a specific regime where the NW growth process is a self-regulated system, the main experimental parameter to select the ZB or WZ phase is the V/III flux ratio. Using an analytical growth model, we show that the V/III flux ratio can be finely tuned by changing the As flux, thus driving the system toward a stationary regime where the wetting angle of the Ga droplet can be maintained in the range of values allowing the formation of pure WZ phase. The analysis of the in situ reflection high energy electron diffraction evolution, combined with high-resolution scanning transmission electron microscopy (TEM), dark field TEM, and photoluminescence all confirm the control of an extended pure WZ segment, more than a micrometer long, obtained by molecular beam epitaxy growth of self- assisted GaAs NWs with a V/III flux ratio of 4.0. This successful controlled growth of WZ GaAs suggests potential benefits for electronics and opto-electronics applications.
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Affiliation(s)
- T Dursap
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
| | - M Vettori
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
| | - C Botella
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
| | - P Regreny
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
| | - N Blanchard
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - M Gendry
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
| | - N Chauvin
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, INSA de Lyon, 7 Avenue Jean Capelle F-69621, Villeurbanne Cedex, France
| | - M Bugnet
- Université de Lyon, INSA de Lyon, Université Claude Bernard Lyon 1, MATEIS, UMR 5510 CNRS, Avenue Jean Capelle, F-69621 Villeurbanne, France
| | - A Danescu
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
| | - J Penuelas
- Institut des Nanotechnologies de Lyon-INL, UMR 5270 CNRS, Université de Lyon, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully cedex, France
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