[15a-313-1~11] 15.3 III-V-group epitaxial crystals, Fundamentals of epitaxy

▲ [15a-313-3] Photoluminescence Properties of GaSb/GaAs Quantum Dots Grown on Ge and GaAs Substrates

〇(D)Zon Zon^1,4, Supachok Thainoi¹, Suwit Kiravittaya², Aniwat Tandaechanurat³, Somsak Panyakeow¹, Yasutomo Ota⁴, Satoshi Iwamoto⁴, Yasuhiko Arakawa⁴ (1.Semiconductor Device Research Laboratory (SDRL), Chulalongkorn University, Bangkok, Thailand, 2.Advanced Optical Technology (AOT) Laboratory, Naresuan University, Phitsanulok, Thailand, 3.International School of Engineering (ISE), Chulalongkorn University, Bangkok, Thailand, 4.Institute for Nano Quantum Information Electronics and Institute of Industrial Science, The University of Tokyo, Tokyo, Japan)

Keywords:GaSb/GaAs Quantum Dots, Optical Properties, QDs Morphology

Zero-dimensional quantum-dot (QD) nanostructure is an interesting structure for both study of physics and device applications [1]. Optoelectronic devices based on a combination of group IV and III-V materials systems might offer a new possibility for realizing novel devices. In this work, self-assembled GaSb/GaAs QDs have been grown on both GaAs and Ge substrates and their optical properties are investigated and compared. As shown in Fig. 1(a), a drastic blueshift of QD peak energy from 1.15 eV (QDs grown on GaAs substrate at 450ºC) to 1.23 eV (on Ge substrate at 450ºC) and a further shift to 1.33 eV (on Ge substrate at 500ºC) reveal the influence of substrate materials and growth temperature on optical properties of GaSb/GaAs QDs. Thermal activation energy Ea is extracted from the experimental results by fitting the integrated PL intensity of QDs peaks with Arrhenius’s equation [2], as shown in Fig. 1(b). We attribute the low Ea values (20-56 meV) for all samples to the weak confinement potential for holes in our QDs, compared with 130 meV observed in the previous report [3]. The lower Ea values for QDs grown on Ge substrate than that of QDs grown on GaAs substrate are resulted from the smaller average height of QDs on Ge substrate. The QDs heights on Ge and GaAs substrates; ~5 nm and ~7 nm are observed by atomic force microscopy. This work enhances our understanding on the optical properties of GaSb/GaAs nanostructures when grown on various substrates and temperatures.
References: [1]Y. Arakawa and H. Sakaki, Appl. Phys. Lett. 40, 939 (1982). [2] R. Songmuang, S. Kiravittaya, M. Sawadsaringkarn, S. Panyakeow, O. G. Schmid, J. Crys. Grow. 251, 166 (2003). [3] K. Suzuki, R. A. Hogg, and Y. Arakawa, J. Appl. Phys. 85, 8349 (1999).