Magnetophonon effect in GaAs and InP to high pressures

Abstract

The magnetophonon effect in high purity epitaxial n-type GaAs and InP has been observed to 15 kbar at 295K using a non-magnetic high pressure apparatus constructed largely of Ti and designed for use with a 90 kG solenoid magnet. The magnetic field shifts of the rho xx magnetophonon extrema with pressure were linear to 15 kbar. After correcting for the change in longitudinal optical phonon frequency with pressure, dm*/dP for the central Gamma 1C conduction band minimum was determined as 0.70 and 0.62%/kbar for GaAs and InP respectively. Agreement with simple four band k.p theory was obtained with energy gap pressure coefficients (dEg/dP) of 11.5+or-0.3*10-6 eV/bar (GaAs) and 9.5+or-0.4*10-6 eV/bar (InP). The pressure shift of the magnetophonon effect in the Hall voltage ( rho xy) was also observed for GaAs. The amplitudes of both rho xx and rho xy oscillations show a small increase with pressure. This is interpreted in terms of the possible scattering mechanisms.