Determination of the LO-phonon and Γ→L intervalley scattering time in GaAs from hot electron luminescence spectroscopy

Abstract

Both the LO-phonon scattering time and the Γ→L intervalley scattering time for electrons in the conduction band of GaAs are of fundamental importance, and they are needed for the modelling of devices. We measure the steady state distribution of hot electrons in lightly p-doped bulk GaAs under carrier densities of 10 13–10 14cm −3, which is orders of magnitude lower than in pulsed laser experiments. Using a 16×16 k.p Hamiltonian and taking into account the transition matrix elements in a dipole model, we determine the hot electron lifetime from comparison with the experimentally found lifetime broadening. For electrons with a kinetic energy of 100meV to 300meV we obtain τ LO =(132±10) fs. We also determine the Γ→L intervalley separation as E ΓL =(300±10) meV. We find Γ→L scattering times around 150fs to 200fs, corresponding to a value for the associated deformation potential of D ΓL =(9.4±1.5)×10 8 eV/ cm.