High-Temperature Microwave Performance of Submicron AlGaN/GaN HEMTs on SiC

The effect of temperature on the small-signal radio-frequency (RF) performance of submicron AlGaN/GaN high-electron-mobility transistors on SiC has been studied from room temperature (RT) up to 600 K. A relation between ambient and channel temperatures has been established by means of finite-element simulations. The thermal behavior of the intrinsic parameters C(gs), C(gd), g(m, int), and g(ds) has been extracted accurately from RF measurements by means of the small-signal equivalent circuit. Main dc parameters (I(D), g(m, ext)) show reductions close to 50% between RT and 600 K, mainly due to the decrease in the electron mobility and drift velocity. In the same range, f(T) and f(max) suffer a 60% decrease due to the reduction in g(m, ext) and a slight increase of C(gs) and C(gd). An anomalous thermal evolution of C(gd) at low I(D) has been identified, which is indicative of the presence of traps.