We have studied experimentally the effect of ambient temperature on performance of the surface-passivated Al0.2Ga0.8N/GaN heterostructure field-effect transistors in the temperature range from 25°C to 250°C. The measured data have been compared with physics-based modeling of the GaN transistor characteristics under different ambient temperatures. The experimental data, showing about 33% degradation in the saturation current with a temperature increase from 25°C to 250°C, agrees well with the results of simulations performed using ISE DESSIS software. Obtained results and analytical extrapolations can be used for predicting device performance in changing environments, as well as for optimization of the device structure.
