期刊
NANOPHOTONICS
卷 9, 期 1, 页码 101-111出版社
WALTER DE GRUYTER GMBH
DOI: 10.1515/nanoph-2019-0328
关键词
AlGaN undershell; point defect diffusion; internal quantum efficiency (IQE); nanowires (NWs); GaInN/GaN MQS
资金
- MEXT Program for research and development of next-generation semiconductor to realize energy-saving society
- MEXT Private University Research Branding Project
- JSPS KAKENHI [15H02019, 17H01055, 16H06416]
- Japan Science and Technology CREST [16815710]
The superior crystalline quality of coaxial GaInN/GaN multiple-quantum shell (MQS) nanowires (NWs) was demonstrated by employing an AlGaN undershell during metal-organic chemical vapor deposition. Scanning transmission electron microscopy (STEM) results reveal that the NW structure consists of distinct GaInN/GaN regions on different positions of the NWs and the cores were dislocation-free. High-resolution atomic contrast STEM images verified the importance of AlGaN undershells in trapping the point defects diffused from n-core to MQSs (m-planes), as well as the improvement of the grown crystal quality on the apex region (c-planes). Time-integrated and time-resolved photoluminescence (PL) measurements were performed to clarify the mechanism of the emission within the coaxial GaInN/GaN MQS NWs. The improved internal quantum efficiency in the NW sample was attributed to the unique AlGaN undershell, which was able to suppress the point defects-diffusion and reduce the dislocation densities on c-planes. Carrier lifetimes of 2.19 ns and 8.44 ns were derived from time-resolved PL decay curves for NW samples without and with the AlGaN undershell, respectively. Hence, the use of an AlGaN undershell exhibits promising improvement of optical properties for NW-based white and micro light-emitting diodes.
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