Monte Carlo analysis of thermal effects in the DC and AC performance of AlGaN/GaN HEMTs

Abstract

The influence of thermal effects in AlGaN/GaN HEMTs is studied by means of Monte Carlo simulations. Measured output and transfer characteristics of a transistor are well reproduced using two techniques, a thermal-resistance method and an electrothermal model which solves the steady-state heat-conduction equation. The validity of the model to reproduce the experimental results is checked in two-terminal structures and transistors. Both methods are also employed to investigate in AC regime in terms of the elements of the small-signal equivalent circuit, providing a good agreement with experimental values, with no significant differences between the models. Apart from the expected decrease of transconductance and drain conductance, the gate to source capacitance is also found to be lowered by heating effects.