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Applied Science and Convergence Technology 2023; 32(1): 12-15
Published online January 30, 2023
https://doi.org/10.5757/ASCT.2023.32.1.12
Copyright © The Korean Vacuum Society.
Post-Annealing Effects on Optical Properties of GaAs/AlGaAs Quantum Dots Grown by Droplet Epitaxy
You Ryang Seoa , Taein Kanga , Jong Su Kima , ∗ 
, Jin Dong Songb , Sang Jun Leec , and Heedae Kimd
aDepartment of Physics, Yeungnam University, Gyeongsan 38541, Republic of Korea
bCenter of Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
cDivision of convergence Technology, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea
dMajor of Semiconductor Science & Technology, Jeonbuk National University, Jeonju 54896, Republic of Korea
Correspondence to:jongsukim@ynu.ac.kr
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The effects of annealing temperature on optical properties for low-temperature growth (LTG) GaAs/AlGaAs quantum dots (QD) were investigated in this study. The LTG GaAs QDs were annealed at temperature of 650, 700, and 750 ∘C. From the photoluminescence (PL) results, we found that the PL intensity was enhanced as the annealing temperature was increased and the emission wavelength blue-shifted with increasing annealing temperature. We confirmed that the crystal quality of LTG QD could be improved due to the thermal quarrying effect. The GaAs QD size could be smaller due to Ga out-diffusion and Al inter-diffusion during the thermal annealing process. In photoreflectance spectra, the Franz-Keldysh oscillations above the GaAs band gap become stronger with increasing annealing temperature. The interface electric field strength also increases due to the decrease in the defect density. We thus found that the defect density could be decreased by increasing the annealing temperature.
Keywords: Droplet epitaxy, GaAs, AlGaAs, Quantum dots, Photoreflectance
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