In0.5Ga0.5As quantum dot intermixing and evaporation in GaAs capping layer growth

Our study of GaAs growth over self-assembled In0.5Ga0.5As quantum dots grown by metalorganic vapor-phase epitaxy showed that GaAs capping layer surface morphology at the onset strongly depended on temperature. Incompletely capped In0.5Ga0.5As islands were elongated toward [110], indicating anisotropy in intermixing. During higher-temperature growth interruption, islands show craters in quantum dot centers. Craters become hexagonal holes whose depth matches GaAs capping layer thickness. Postannealing photoluminescence spectra show no peak corresponding to overly large quantum dot radiation, indicating that growth interruption after capping layer formation at a certain thickness eliminates overly large quantum dots. (C) 1998 American Institute of Physics. [S0021-8979(98)00924-4].