Hot electron energy relaxation in AlGaN/GaN heterostructures

摘要

We report measurements of the rate of energy loss per electron, P_e, by a two-dimensional electron gas in a series of AlGaN/GaN heterostructures grown on different substrates by MBE. The measurements cover a range of electron temperatures, T_e, from 4-40 K. A combination of zero and high magnetic field electrical transport measurements was used to determine T_e as a function of the power dissipated in the device. It was found that for the samples grown on the better lattice matched substrates P_e ∝ T_e~n, with n = 5 at the lowest temperatures, T_e 10 K. At higher temperatures, T_e > 10 K, n → 1 in all samples. The experimental results are compared with numerical calculations of the energy relaxation rate. We find that the emission of piezoelectrically coupled acoustic phonons is the dominant energy loss process in the studied temperature range.