Acoustic phonon scattering in a low density, high mobility AlGaN/GaN field effect transistor

Abstract

We report on the temperature dependence of the mobility, $\hat{I}¼$, of the two-dimensional electron gas in a variable density AlGaN/GaN field effect transistor, with carrier densities ranging from 0.4$\times 10^{12}$ cm${}^{-2}$ to 3.0$\times 10^{12}$ cm${}^{-2}$ and a peak mobility of 80,000 cm${}^2$/Vs. Between 20 K and 50 K we observe a linear dependence $\hat{I}{¼}_{ac}^{-1}=\hat{I}\pm$T indicating that acoustic phonon scattering dominates the temperature dependence of the mobility, with $\hat{I}\pm$ being a monotonically increasing function of decreasing 2D electron density. This behavior is contrary to predictions of scattering in a degenerate electron gas, but consistent with calculations which account for thermal broadening and the temperature dependence of the electron screening. Our data imply a deformation potential D = 12-15 eV.

3 pages, 2 figures, RevTeX. Submitted to Appl Phys Lett