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

Our study of GaAs growth over self-assembled In0.5Ga0.5As quantum dots grow n by metalorganic vapor-phase epitaxy showed that GaAs capping layer surfac e morphology at the onset strongly depended on temperature. Incompletely ca pped In0.5Ga0.5As islands were elongated toward [110], indicating anisotrop y in intermixing. During higher-temperature growth interruption, islands sh ow craters in quantum dot centers. Craters become hexagonal holes whose dep th matches GaAs capping layer thickness. Postannealing photoluminescence sp ectra show no peak corresponding to overly large quantum dot radiation, ind icating that growth interruption after capping layer formation at a certain thickness eliminates overly large quantum dots. (C) 1998 American Institut e of Physics. [S0021-8979(98)00924-4].