Intervalley and electron-electron scattering rates measured in p-GaAs with hot electron luminescence

Abstract

Recombination of a free electron at the conduction band minimum with a neutral acceptor causes the prominent (e, A0) luminescence peak near the band gap of p-GaAs. Although the resulting emission is orders of magnitude weaker, electrons well above the conduction band minimum can also radiatively recombine with neutral acceptors. At low optically injected densities, it has been shown previously that there is a rich oscillatory structure to this hot (e, A0) spectrum, resulting from the cascade nature of the electron cooling by LO phonon emission. From a simple analysis of the spectra as a function of the initial electron energy, the authors have determined intervalley scattering rates in GaAs as a function of energy at electron densities low enough that carrier-carrier scattering is unimportant. At injected densities <1010 cm-3 , the oscillatory structure smears out as a result of electron-electron scattering. By studying the spectral shape as a function of injected density, they have been able to determine quantitatively the electron scattering rates.