Hot Carrier Relaxation by Extreme Electron-LO Phonon Scattering in GaN

Abstract

Hot carrier relaxation has been investigated in GaN using non-resonant femtosecond excitation where electrons are excited above and below the LO phonon energy. We observe remarkably rapid electron relaxation; the electron distribution is non-thermal, with a “cut-off” occurring near ELO. In a preliminary Monte Carlo study we have simulations which reproduce the major experimental observations, confirming the development of a non-thermal electron distribution near ELO due to the strong electron–LO phonon interaction. Hot phonon effects are pronounced at high carrier densities.