Non-uniform stress effects in GaN based heterojunction field effect transistors

We present results from numerical simulations of an AlGaN/GaN heterostructure field effect transistor. Simulations include a polarization model that accounts for non-uniform stress fields and compare results for devices containing uniform and non-uniform stress distributions. Simulations of the electrical characteristics focus on piezoelectric polarization effects. Due to the high stiffness of nitrides, even large stresses in overlayers lead to relatively minor DC and transient electrical effects. Piezoelectric polarization effects are more pronounced for devices with larger AlGaN film strain relaxation.