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, gm, int, and g _ds has been extracted accurately from RF measurements by means of the small-signal equivalent circuit. Main dc parameters (ID, gm, 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, fT and f _max suffer a 60% decrease due to the reduction in gm, ext and a slight increase of C _gs and C _gd. An anomalous thermal evolution of C _gd at low ID has been identified, which is indicative of the presence of traps.