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Thermally Introduced Bismuth Clustering in Ga(P,Bi) Layers under Group V Stabilised Conditions Investigated by Atomic Resolution In Situ (S)TEM. Sci Rep 2018; 8:9048. [PMID: 29899349 PMCID: PMC5998072 DOI: 10.1038/s41598-018-27286-4] [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: 12/14/2017] [Accepted: 05/30/2018] [Indexed: 11/08/2022] Open
Abstract
We report the formation of Bi clusters in Ga(P1-x,Bix) layers during an in situ (scanning) transmission electron microscopy ((S)TEM) annealing investigation. The non-destructive temperature regime in dependence on the tertiarybutylphosphine (TBP) pressure in the in situ cell was investigated to ensure that the results are not distorted by any destructive behaviour of the crystal during the thermal treatment. The following annealing series of the Ga(P92.6Bi7.4) and Ga(P96.4Bi3.6) layers reveals that the threshold temperature at which the Bi clustering takes place is 600 °C in the Ga(P92.6Bi7.4) layer. Further thermal treatments up to 750 °C show a relationship between the Bi fraction in the Ga(P1-x,Bix) layer and the initial temperature at which the Bi clustering takes place. Finally, we investigate one Bi cluster at atomic resolution conditions. In these conditions, we found that the Bi cluster crystallized in a rhombohedral phase, aligning with its {101} planes parallel to the Ga(P,Bi) {202} planes.
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Zhang L, Wu M, Chen X, Wu X, Spiecker E, Song Y, Pan W, Li Y, Yue L, Shao J, Wang S. Nanoscale distribution of Bi atoms in InP 1-xBi x. Sci Rep 2017; 7:12278. [PMID: 28947809 PMCID: PMC5612989 DOI: 10.1038/s41598-017-12075-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 09/04/2017] [Indexed: 11/09/2022] Open
Abstract
The nanoscale distribution of Bi in InPBi is determined by atom probe tomography and transmission electron microscopy. The distribution of Bi atoms is not uniform both along the growth direction and within the film plane. A statistically high Bi-content region is observed at the bottom of the InPBi layer close to the InPBi/InP interface. Bi-rich V-shaped walls on the (-111) and (1-11) planes close to the InPBi/InP interface and quasi-periodic Bi-rich nanowalls in the (1-10) plane with a periodicity of about 100 nm are observed. A growth model is proposed to explain the formation of these unique Bi-related nanoscale features. These features can significantly affect the deep levels of the InPBi epilayer. The regions in the InPBi layer with or without these Bi-related nanostructures exhibit different optical properties.
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Affiliation(s)
- Liyao Zhang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China
| | - Mingjian Wu
- Institute of Micro- and Nanostructure Research & Center for Nanoanalysis and Electron Microscopy (CENEM), Department of Materials Science, Universität Erlangen-Nürnberg, Cauerstraße 6, D-91058, Erlangen, Germany
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117, Berlin, Germany
| | - Xiren Chen
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, CAS, 500 Yutian Road, Shanghai, 200083, China
| | - Xiaoyan Wu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China
| | - Erdmann Spiecker
- Institute of Micro- and Nanostructure Research & Center for Nanoanalysis and Electron Microscopy (CENEM), Department of Materials Science, Universität Erlangen-Nürnberg, Cauerstraße 6, D-91058, Erlangen, Germany
| | - Yuxin Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China
| | - Wenwu Pan
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China
| | - Yaoyao Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China
| | - Li Yue
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China
| | - Jun Shao
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, CAS, 500 Yutian Road, Shanghai, 200083, China
| | - Shumin Wang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Changning Road, Shanghai, 200050, China.
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden.
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Wood AW, Chen W, Kim H, Guan Y, Forghani K, Anand A, Kuech TF, Mawst LJ, Babcock SE. Annealing-induced precipitate formation behavior in MOVPE-grown GaAs 1-x Bi x explored by atom probe tomography and HAADF-STEM. NANOTECHNOLOGY 2017; 28:215704. [PMID: 28471752 DOI: 10.1088/1361-6528/aa6cdb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The effects of a 45 min anneal at 800 °C on the physical properties and microstructure of a five-period GaAs1-x Bi x /GaAs1-y Bi y superlattice with y ≠ x were studied using room-temperature photoluminesence spectroscopy, high-resolution x-ray diffraction, high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM), and atom probe tomography (APT). The anneal resulted in a substantial increase of the photoluminesence intensity over that observed in the as-deposited sample, indicating annihilation of non-radiative recombination centers and stability of the superlattice structure during the anneal. However, some precipitation of Bi from the GaAs1-x Bi x also occurred. The characteristics of phase separation that occurred within these precipitates were investigated in detail by APT and HAADF-STEM. They indicate that the precipitation reaction involves formation of embedded nano-scale liquid droplets that can accelerate local Bi dissolution from the GaAs1-x Bi x matrix by moving through it. Preservation of nanometer scale sharp Bi concentration gradients in the growth direction suggested that very little solid state diffusion of Bi occurred during the anneal. The observed gradient in precipitate number density with distance from the sample surface further supports hypotheses of an enabling role of Ga vacancies in the precipitation process.
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Affiliation(s)
- Adam W Wood
- Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, WI 53706, United States of America
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Patil PK, Luna E, Matsuda T, Yamada K, Kamiya K, Ishikawa F, Shimomura S. GaAsBi/GaAs multi-quantum well LED grown by molecular beam epitaxy using a two-substrate-temperature technique. NANOTECHNOLOGY 2017; 28:105702. [PMID: 28145284 DOI: 10.1088/1361-6528/aa596c] [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
We report a GaAs0.96Bi0.04/GaAs multiple quantum well (MQW) light emitting diode (LED) grown by molecular beam epitaxy using a two-substrate-temperature (TST) technique. In particular, the QWs and the barriers in the intrinsic region were grown at the different temperatures of [Formula: see text] = 350 °C and [Formula: see text] respectively. Investigations of the microstructure using transmission electron microscopy (TEM) reveal homogeneous MQWs free of extended defects. Furthermore, the local determination of the Bi distribution profile across the MQWs region using TEM techniques confirm the uniform Bi distribution, while revealing a slightly chemically graded GaAs-on-GaAsBi interface due to Bi surface segregation. Despite this small broadening, we found that Bi segregation is significantly reduced (up to 18% reduction) compared to previous reports on Bi segregation in GaAsBi/GaAs MQWs. Hence, the TST procedure proves as a very efficient method to reduce Bi segregation and thus increase the quality of the layers and interfaces. These improvements positively reflect in the optical properties. Room temperature photoluminescence and electroluminescence (EL) at 1.23 μm emission wavelength are successfully demonstrated using TST MQWs containing less Bi content than in previous reports. Finally, LED fabricated using the present TST technique show current-voltage (I-V) curves with a forward voltage of 3.3 V at an injection current of 130 mA under 1.0 kA cm-2 current excitation. These results not only demonstrate that TST technique provides optical device quality GaAsBi/GaAs MQWs but highlight the relevance of TST-based growth techniques on the fabrication of future heterostructure devices based on dilute bismides.
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Affiliation(s)
- Pallavi Kisan Patil
- Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime, Japan
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