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Research Paper

Applied Science and Convergence Technology 2019; 28(1): 9-12

Published online January 31, 2019

https://doi.org/10.5757/ASCT.2019.28.1.9

Copyright © The Korean Vacuum Society.

Temperature-Dependent Optical Properties and Bandgap Characteristics of InAs/GaAs Sub-monolayer Quantum Dot Investigated by Photoreflectance Spectroscopy

Minseak Kima,†, Sang Jo Leea,†, Hyun Jun Joa, Geun-Hyeong Kima, Yeong Ho Kimb, Sang Jun Leeb, Christiana B. Honsbergc, and Jong Su Kima,*

aDepartment of Physics, Yeungnam University, Gyeongsan 38541, Korea, bKorea Research Institute of Standards and Science, Daejeon 34113, Korea, cSchool of Electrical, Computer and Energy Engineering, Arizona State University, Arizona 85287, USA

Correspondence to:*jongsukim@ynu.ac.kr

Received: November 29, 2018; Revised: January 29, 2019; Accepted: January 29, 2019

Abstract

InAs/GaAs submonolayer quantum dots (SML-QD) were investigated by temperature dependent photoreflectance (PR) spectroscopy. To investigate the optical properties of SML-QD, GaAs and InAs SML-QD related PR spectra were monitored at different temperatures. Two notable signals were observed in the SML-QD and GaAs regions. The PR spectra of SML-QD region were interpreted by the third-derivative functional form method. We observe the oscillatory signal above the GaAs band gap energy (Eg) due to the Franz-Keldysh effect caused by an interface electric field (F). At room temperature, the PR transition of SML-QD was obtained at near ~1.3 eV with a broadening of 29.5 meV. The F was obtained from the Aspnes’ numerical PR analysis. The F was changed from 14 to 12 kV/cm by decreasing the temperature from 300 to 140 K causing a thermal induced carrier distribution near the interfaces.

Keywords: Submonolayer quantum dot, Photoreflectance, InAs/GaAs

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