Crystal, impurity-related and growth defects in molecular beam epitaxial GaAs layers

Abstract

Crystallographic defects in GaAs layers grown by molecular beam epitaxy were studied. The methods used were photochemical etching, developed previously, and also optical and scanning electron microscopy. Dislocations, stacking faults, impurity microprecipitates and impurity out-diffusion from the substrate were observed. Large growth defects, namely oval defects and whiskers, were also studied using selective etching, transmission electron microscopy and electron microprobe analysis. The roles of the substrate quality, handling, surface preparation and epitaxial growth conditions were considered in connection with the formation of the crystallographic defects.