Thermodynamic study of phase equilibria in strained III-V alloy semiconductors

Abstract

Phase equilibria in GaSb-GaAs and InAs-GaAs thin films grown on GaAs and InP substrates were calculated, taking into consideration the elastic contribution caused by the lattice mismatch between the film and substrate. The basic concept used in describing the elastic free energy is that strain due to a lattice mismatch accumulates in a thin film and interfacial misfit dislocations form when the strain energy exceeds a certain energy barrier. Our calculations showed that the single-phase region of a zinc-blend-type compound forms in the GaSb-GaAs/InP and InAs-GaAs/InP systems. This result is in fairly good agreement with the experimental examination of epitaxially grown thin film. The compositional latching phenomenon frequently observed in alloy semiconductor systems can be interpreted in terms of the phase separation generated by the accumulated strain in the thin films.