Energy relaxation by hot carriers in wurtzite GaN epilayers

In this paper, we report hot carrier energy relaxation processes studied by acoustic phonon emission in wurtzite GaN epilayers, using the heat pulse t echnique. In this method, the carriers were heated up by means of short (ap proximate to 10 ns) voltage pulses and emitted phonons were detected by Al bolometers biased at their superconducting transition. Obtained phonon sign als indicate that the optical phonon emission threshold has not been reache d and longitudinal acoustic and transverse acoustic modes can be clearly re solved. This paper specifically concentrates on the electron temperature de pendence of the energy relaxation rates and compares the experimental resul ts with the existing theory.