Resonant excitation of bound exciton luminescence in GaAs 1−xP x alloys

Abstract

Bound exciton luminescence in GaAs 1−xP x alloys is sufficiently broadened by alloy disorder that little information can be gained about electronic energies and phonon couplings. By resonantly exciting narrow exciton components with a dye laser we have recovered sharp luminescence features like those in GaP. Detailed results are given for x=0.50 where broadening is greatest. Excitons bound to group VI donors show phonon coupling characteristic of an effective mass level at the X 1 conduction band minimum, whereas nitrogen traps show phonon assistance characteristic of a deep level--stronger coupling to phonons throughout much of k -space and more zero phonon broadening. We identify phonons and verify zero-phonon luminescence lineshape for both cases.