Neural Sensory Processing Group

We report on the temperature dependence of the mobility 􏲏 of the two-dimensional 􏲋2D􏲊 electron gas in a variable density AlGaN/GaN field-effect transistor, with carrier densities ranging from 0.4􏱬1012 to 3.0􏱬1012 cm-2 and a peak mobility of 80 000 cm2/V s. Between 20 and 50 K we observe a linear dependence 􏲏-1=􏲎T, indicating that acoustic phonon scattering dominates the ac temperature dependence of the mobility, with 􏲎 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 that account for thermal broadening and the temperature dependence of the electron screening. Our data imply a deformation potential D =12\textendash 15 eV.