Influence of crystallization temperature on InP ring-shaped quantum-dot molecules grown by droplet epitaxy

We have studied the influence of crystallization temperature on the structural and optical properties of InP ring-shaped quantum-dot molecules (QDMs) grown by solid-source molecular-beam epitaxy (MBE) using droplet epitaxy technique. The surface morphologies and photoluminescence spectra were examined by ex situ atomic force microscopy (AFM) and micro-photoluminescence (micro-PL) measurement. The increasing of crystallization temperature results in the decreasing of InP quantum-dot (QD) and ring-shaped QDM densities while average outer and inner diameters of InP ring-shaped QDMs become larger. The distributions of the number of InP QDs per InP ring-shaped QDMs, lateral size of InP QDs, height of InP QDs and height and lateral size relative distributions of InP QDs have been statistically investigated. The photoluminescence peaks of InP ring-shaped QDMs are red-shifted when crystallization temperature increases. (C) 2009 Elsevier B.V. All rights reserved.