TCAD accurate modeling of trap-induced effects in GaN HEMTs

In this work we demonstrate an accurate Technology Computer Aided Design (TCAD) modeling approach for the analysis of trap effects on the electrical features of AlGaN/GaN HEMT devices for microwave applications. The physical device model includes the discretized coupled drift-diffusion and trap rate equations system, implemented into an in-house mixed-mode TCAD simulator, and solved in dynamic conditions with the Harmonic Balance (HB) algorithm. The TCAD allows a seamless assessment of the DC, small-signal AC and periodic large-signal (LS) behavior of GaN HEMTs as a function of the trap properties. A test-case addresses the analysis of 29 GHz class B power amplifier based on a Fe-doped 150 nm GaN HEMT as a function of the Fe trap energy, showing that, despite a marked signature on the AC parameters dispersion, traps have a mild impact on single-tone LS behavior even in strongly non-linear operation.