Non-equilibrium electron distributions and electron-longitudinal optical phonon scattering rates in wurtzite GaN

Non-equilibrium electron distributions and electron-longitudinal optical phonon scattering rates in wurtzite GaN have been studied by subpicosecond time-resolved Raman spectroscopy. Our experimental results show that for electron densities n ≥ 5 × 10¹⁷cm^-3, the non-equilibrium electron distributions in wurtzite GaN can be very well described by Fermi-Dirac distribution functions with the effective electron temperature much higher than the lattice temperature. In addition, we find that the total electron-longitudinal optical phonon scattering rate in GaN is about one order of magnitude larger than that in GaAs. We attribute this enormous increase in the electron-longitudinal optical phonon scattering rate to the much larger ionicity in GaN.