Intervalley Γ-X Deformation Potentials in III-V Zincblende and Si Semiconductors by Ab Initio Pseudopotential Calculations

Abstract

Intervalley Γ-X deformation potential constants (IVDP's) have been calculated by first principle pseudopotential method for the III-V zincblende semiconductors A1p, A1As, A1Sb, Gap, GaAs, GaSb, InP, InAs and InSb. As a prototype crystal we have also carried out calculations on Si. When comparing the calculated IVDP's of LA phonon for Gap, InP and InAs and LO phonon for A1As, A1Sb, GaAs, GaSb and InSb with a previous calculation by EPM in rigid approximation, good agreements are found. However, our ab initio pseudopotential results of LA phonon for A1As, A1Sb, GaAs, GaSb and InSb and LO phonon for Gap, InP and ZnAs are about one order of magnitude smaller than those obtained by EPM calculations, which indicate that the electron redistributions upon the phonon deformations may be important in affecting Γ-X intervalley shatterings for these phonon modes when the anions are being displaced. In our calculations the phonon modes of LA and LO at X point have been evaluated in frozen phonon approximation. We have obtained, at the same time, the LAX and LOX phonon frequencies for these materials from total energy calculations. The calculated phonon frequencies agree very well with experimental values for these semiconductors.