Authors: P. HAWKER, A. J. KENT, T. S. CHENG, C. T. FOXON
Abstract: We have measured the energy relaxation rate of hot electrons in MBE grown bulk GaN epilayers on GaAs and sapphire substrates over the electron temperature range 1 - 130 K. The measurements were made using heat pulse techniques. For layers grown on GaAs substrates the results show that the carriers reside in the substrate, probably as in a GaAs/AlGaAs heterojunction. For layers grown on sapphire substrates we obtain a P \propto T^4_e dependence for the relaxation rate in the low temperature limit, consistent with piezoelectric coupling in the so-called `dirty' regime, changing to a linear dependence in the high temperature, equipartition, regime.
Full Text: PDF