MICROSTRUCTURAL CHARACTERISTICS OF MIXED III-V EPITAXIAL LAYERS

Some of the microstructural characteristics of phase separated and atomically ordered mixed m-V layers are reported. It is shown that phase separation is two-dimensional in nature and occurs along elastically soft directions lying in a growth plane while the layer is growing. The resulting microstructure is stable at the surface, but is unstable in the bulk. Atomic ordering also evolves at the surface and produces double and triple period superlattices along [111] directions. It is driven by surface reconstruction-induced sub-surface stresses which bias the occupation of sites by atomic species differing in their covalent tetrahedral radii. Its evolution entails rearrangement of atoms within the phase separated microstructure that may be occurring at step edges.