Simulation of trap state effects in GaN DHFETs on buffer leakage current and breakdown voltage

Influence of deep level trap states on the buffer leakage current of enhanced AlGaN/GaN/AlGaN double-heterostructure FETs have been studied. The relationship between the buffer leakage current and the breakdown voltage (V_br) of the device with different trap density and trap energy level in the AlGaN buffer layer was simulated. It is showed that the simulation results of the buffer leakage current and breakdown voltage by optimizing the trap density and trap energy level are consistent with the experimental data. The breakdown voltage increases linearly with the gate-to-drain distance (L_gd) and the highest V_br of 2300V is achieved by optimization.