POLAR OPTIC PHONON AND GAMMA-]L INTERVALLEY SCATTERING TIMES IN GAAS FROM STEADY-STATE HOT-ELECTRON LUMINESCENCE SPECTROSCOPY

We deduce the Γ→L intervalley and polar optic phonon scattering times of hot electrons in bulk GaAs from cw hot (e,A0) luminescence spectra at low excitation densities and their dependence on electron kinetic energy. We obtain the lifetime broadening due to these two processes from comparison with line shape calculations using a 16×16 k center-dot p Hamiltonian, a full integration over k space, and a dipole model for the optical matrix elements. We find for the LO-phonon emission time τLO= (132±10)fs. The threshold for Γ→L scattering is determined as 330±10 meV, above which a distinct decrease in total lifetime is observed. Γ→L scattering times of 150-200 fs are deduced, and we discuss a corresponding deformation potential.