Phase Separation In III-V Semiconductors

Abstract

ABSTRACTData are presented to show the morphological instability as well as the occurrence of 1-dimensional phase separation through the spinodal decomposition process in the strained layer heteroepitaxy of short-period superlattices. Biaxial strain has been attributed to be the driving force. With a large net strain in the epitaxial film, > 3.5%, island growth of (InAs)1/(GaAs)1 on GaAs is observed. With a near zero net strain, however, 1-dimensional lateral compositional modulation is observed in the growth of (InAs)2/(GaAs)2 on InP and (InP)2/(GaP)2 on GaAs substrates. Both surface reaction and bulk diffusion take part in forming the ultimate modulation. A small but definitive hydrostatic strain in the metastable Al0.3Ga0.7As film grown at low temperature induces also a 1-dimensional compositional modulation upon annealing at 600°C, a direct evidence of the existence of a miscibility gap in strained AlxGa1-xAs.