Distribution of self-assembled InAs dots on patterned GaAs (1 0 0) substrates

Abstract

We have used pre-growth patterning of a (1 0 0) GaAs substrate into mesas to modify the nucleation of InAs quantum dots (QDs) grown by molecular beam epitaxy. The distribution of InAs quantum dots has been assessed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). On stripe mesas patterned with their long axis in the [ 0 1 1 ¯ ] and [0 1 1] directions, we observe a narrowing of the mesa width during GaAs overgrowth for the growth conditions used. We have observed several different distributions of dots such as; a single line of dots, dots clustered along the edges of the mesa or the top of the mesa being totally covered with dots. These distributions depend on the net migration of indium adatoms on the sidewall facets, the underlying GaAs surface morphology and width of the mesa top (1 0 0) plane.