Energy relaxation by warm two-dimensional electrons in a GaN/AlGaN heterostructure

The rate of energy loss per electron, P e , by a two-dimensional electron gas in an GaN/AIGaN heterostructure has been measured as a function of electron temperature, T e , in the range 0.4-35 K. A combination of zero and high magnetic field electrical transport measurements were used to determine T e as a function of the power dissipated in the device. It was found that P e T n e , with n 5 at the lowest temperatures, T e « 2 K, while for higher temperatures, T e > 10 K, n → 1. The experimental results are compared with numerical calculations of the energy relaxation rate. In the range of temperatures studied, emission of piezoelectrically coupled acoustic phonons was found to be the dominant energy relaxation mechanism.