Rapid cooling of uncapped indium arsenide quantum dot surfaces grown in Stranski-Krastanow mode by MBE

Abstract

We report a method to significantly improve the density of quantum dots (QD) grown by molecular beam epitaxy. The use of high As₄ (tetrameric arsenic) beam equivalent pressure during Stranski-Krastanow growth led to low density QD formation as seen from cross-section transmission electron microscopy (XTEM). By rapidly cooling this uncapped low density QD layer of critical coverage from the growth temperature of 490°C to 300°C, we were able to effect several orders of magnitude increase in density and enhanced uniformity. Atomic force microscopy (AFM) of surfaces reveal more pronounced density enhancement in QDs grown at higher As₄ pressure. This effect is explained on the basis of Group III adatom condensation and surface diffusion.