Effect of Buried depth, Thickness of Channel and Gate length on Breakdown Voltage in AlGaN/GaN HEMT

In this work, effect of conventional AlGaN/GaN HEMT with non recessed channel (NR-HEMT) on breakdown voltage is presented for different depth of buried region and thickness of channel. We proposed NR-HEMT incorporated with optimized buried gate depth and thickness of channel termed as channel recessed buried gate AlGaN/GaN HEMT (CRBG-HEMT) for which breakdown voltage is observed to be enhanced resulting from lowered electric field peak at the gate edge. The proposed device is investigated for different gate lengths with fixed buried depth of 5 nm and thickness of channel 300 nm using TCAD simulations. The extracted breakdown voltage behaviour and electric field profile of NR-HEMT and CRBG-HEMT are illustrated. It is found that breakdown voltage of proposed device is improved when compared to NR-HEMT with buried gate (NRBG-HEMT) and NR-HEMT with channel recess (CR-HEMT) by 6.7% and 40.2%, respectively. However, the maximum drain current in CRBG-HEMT device is observed to decrease by 8% compared to the NR-HEMT device, due to an increased threshold voltage and a reduction in two-Dimensional Electron Gas (2DEG) density in the channel.