Investigation of the High-Temperature Operation of AlGaN/GaN HFETs via Studying the Impact of Temperature Dependency of Drift Transport Characteristics

Investigation of the reliable operation of AlGaN/GaN HFETs at elevated temperatures is attempted. In this paper, a Monte Carlo-based temperature-dependent mobility model, with incorporation of steady-state velocity overshoot, is employed in modeling the drain current-voltage characteristics of AlGaN/GaN HFETs at 300, 400, and 500 K. One of the major merits of this model is that it employs a very small set of fitting parameters. The modeled drain current-voltage characteristics have been successfully matched to the experimental characteristics at the aforementioned temperatures. While confirming that a brief measurement at these temperatures is of no reliability concern on the quality of the metal-semiconductor contacts, this matching proves that the temperature dependency of the electron drift velocity is the cause of the degradation of drain current within the aforementioned range of temperature. In producing the aforementioned match for the long-gate AlGaN/GaN HFETs, it is also shown that the accurate modeling of the temperature dependency of the low-field drift transport is more consequential than the accurate representation of the transport in the medium-to-high electric fields.