In mixed III–V layers atomic species having different covalent tetrahedral radii were not distributed at random on their respective sub-lattices. Two types of deviation from randomness were observed: phase separation and atomic ordering. Phase separation was two-dimensional in nature, occurred on the surface while the layer was growing and was driven by surface thermodynamics. In contrast, atomic ordering was induced by sub-surface stresses associated with (2 x 4) and (2 x 3) reconstructions of group-V terminated (001) surfaces. These stresses bias the occupation of sites by atomic species differing in their tetrahedral radii and this feature led to the evolution of double and triple period superlattices on (¯111)B, (1¯11)B, and (111)A, (11¯1)A planes respectively.

Two-Dimensional Phase Separation and Surface-Reconstruction Driven Atomic Ordering in Mixed III–V Layers. S.Mahajan: Materials Science and Engineering B, 1995, 30[2-3], 187-96