Comparison of Simulation and Measurement of Gate Leakage Current in Metal/Al2O3/GaN/AlGaN/AlN/GaN Capacitors

We compare the simulations and measurements of gate leakage current in metal-insulator-semiconductor capacitors fabricated on standard AlGaN/GaN transistor layers. In the simulations, a fixed charge density at the interface between the Al₂O₃ layer and the GaN cap layer was assumed for simplicity. The fixed charge layer (which depends on bias and device history) was obtained from capacitance-voltage measurements. The calculated tunneling current due to field emission from localized states in the GaN cap layer agreed with the experimental results. No additional leakage mechanisms had to be invoked.