Influence of InAs Coverage on Transition of Size Distribution and Optical Properties of InAs Quantum Dots

G.S. Kima, S.M. Jeona, M.Y. Choa, H.Y. Choia, D.Y. Kima, M.S. Kima, Y.S. Kwonb, J.W. Choec, J.S. Kimd, J.S. Kime and J.Y. Leema aDepartment of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae 621-749, Korea bATTO Co., Ltd., Shiheung 429-849, Korea cDepartment of Physics, Kyung Hee University, Seoul 130-701, Korea dDepartment of Information Materials Science and Engineering, Chonbuk University, Jeonju 664-14, Korea eDepartment of Physics, Yeungnam University, Gyeongsan 712-749, Korea

Received: May 25, 2009; revised version: April 27, 2010; in final form: June 8, 2010

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The influence of InAs coverage on the formation of self-assembled quantum dots grown by molecular-beam epitaxy was investigated by atomic force microscopy and photoluminescence measurements. As the InAs coverage increased from 2.0 to 3.0 monolayers, the quantum dot density decreased from 1.1 × 1011 to 1.36 × 1010 cm-2. This result could be attributed to the coalescence of neighboring small InAs quantum dots resulting in the formation of much larger InAs quantum dots with lower quantum dot density. Atomic force microscopy results revealed that as the InAs quantum dot coverage increased, the transition of size distribution of InAs quantum dots from single-modal to multimodal occurred. The temperature-dependent photoluminescence spectra showed that the photoluminescence spectra red shifted and the photoluminescence peak intensity decreased as the InAs coverage increased. The thermal activation energy was strongly dependent on the InAs coverage, and for InAs quantum dots with 3.0 ML thick InAs coverage, this energy was estimated to be 147 meV.

DOI: 10.12693/APhysPolA.118.673 PACS numbers: 81.15.Hi, 68.37.Ps, 78.55.Cr, 78.67.Hc