Gate Leakage Current Assessment of AlGaN/GaN HEMT with AlN Cap Layer

In this work, TCAD-based investigation has been performed to explore the influence of AlN cap layer on the reliability of AlGaN/GaN HEMT. Effect of cap layer thickness (AlN) and gate length on gate leakage current, drain current and off-current (Ioff) has also been demonstrated in this study. Using AlN cap layer, higher drain current has been achieved with significantly lower gate leakage current. However, almost same off-state current is achieved by using AlN material instead of GaN-based cap layer. With the enhancement in drain voltage, significant enhancement in gate leakage current is observed which is significantly higher in the device having GaN cap layer. Also, the improvement in gate leakage current with positive gate bias is significantly higher than the negative gate bias.