Abstract:The capacitance-voltage characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTS) are measured in the temperature range of 223–398 K. The dependence of capacitance on frequency at various temperatures is analyzed. At lower temperatures, the capacitance decreases only very slightly with frequency. At higher frequencies the curves for all temperatures tend to one capacitance value. Such behavior can be attributed to the interface states or the dislocations.