Ordered structures and phase states in epitaxial layers of iii–v semiconductor alloys

The conditions for atomic long-range ordering and probable phase states in (001) and (110) epilayers of III–V semiconductor alloys of the A_0.5B_0.5C type have been discussed in terms of a simple phenomenological Ising model taking into account the layer-by-layer stacking sequence of epitaxial growth. The results clearly explain some specific features of the epitaxial phase formation which have been revealed by experiments. It is suggested that the epitaxial growth can develop atomic long-range order even in alloys which have a tendency toward phase separation in the bulk state.