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

Phase equilibria in GaSb-GaAs and InAs-GaAs thin films grown on GaAs and In P substrates were calculated, taking into consideration the elastic contrib ution caused by the lattice mismatch between the film and substrate. The ba sic concept used in describing the elastic free energy is that strain due t o a lattice mismatch accumulates in a thin film and interfacial misfit disl ocations form when the strain energy exceeds a certain energy barrier. Our calculations showed that the single-phase region of a zinc-blend-type compo und forms in the GaSb-GaAs/InP and InAs-GaAs/InP systems. This result is in fairly good agreement with the experimental examination of epitaxially gro wn thin film. The compositional latching phenomenon frequently observed in alloy semiconductor systems can be interpreted in terms of the phase separa tion generated by the accumulated strain in the thin films.