High-pressure phases of III-V zinc-blende semiconductors

With the use of the pseudopotential total-energy approach, the stability of two likely high-pressure structures, the A5 (-Sn) and rocksalt structures, for the III-V compounds AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb are investigated. We present the calculated pressures for the phase transformations and compare them with the experimental values. As previously reported for AlP, there are discrepancies in the transition pressures between theory and experiment for Al compounds and these are discussed. A new high-pressure phase of GaSb analogous to the simple hexagonal structure of Si or Ge is predicted to be stable with a transition from the A5 phase to the hexagonal phase at a pressure of 528 kbar. Using the measured and calculated results for the high-pressure phases of the zinc-blende compounds, we conclude that the rocksalt phase is stabilized relative to the A5 phase by the averaged optical energy gap (both homopolar and heteropolar contributions) of the material.