Reduction of surface defects in GaAs grown by molecular beam epitaxy

Abstract

A method to reduce the density of oval defects originating from pregrowth surface particulates and other contaminants for GaAs layers grown by molecular beam epitaxy (MBE) is presented. It appears that if a thin GaAs buffer layer is deposited by alternately supplying Ga atoms and As4 molecules to a GaAs substrate, prior to further growth by MBE, the density of the oval defects in the final layer is reduced reproducibly by a factor of 7, from about 490 to 70 cm−2, when compared with that obtained using MBE alone under closely similar conditions. The improved surface morphology produced by the pulsed beam method is thought to be related to initial film growth which proceeds likely in a two-dimensional layer-by-layer fashion.