Role of Traps in Gate Leakage Current in p-gate GaN HEMTs Through TCAD Simulations

In this study we exploit technology computer-aided design (TCAD) simulations to investigate the role of traps in the 1D gate stack of p-gate GaN HEMTs, and to fit experimental gate current characteristic. We leverage on the capabilities of Ginestra TCAD software from Applied Materials, which distinctive feature is to link material defects and traps to device performance and reliability (Materials To Device Simulation [1]). We demonstrate that accurate gate leakage modelling requires both direct tunneling and trap-assisted tunneling (TAT) to be included in the simulation, besides thermionic emission. Tuning the trap position and density, we show that a good fit to experiments can be obtained only when p-GaN traps, namely N-vacancies, and AlGaN traps are both present.