Photoluminescence excitation of the 0.77-eV emission in undoped semi-insulating GaAs

Abstract

Photoluminescence excitation spectra have been obtained at 4.2 K for the 0.77-eV broad emission band present in undoped semi-insulating GaAs. The oscillating structures at the above-band-gap energy can be attributed to the energy relaxation of the conduction-band electron by the successive emission of the zone-center longitudinal phonon. The electron capture into the deep donor responsible for the 0.77-eV emission is made through a shallow donor state. The possible radiative mechanism of the 0.77-eV emission is discussed.