Performance Enhancement of Normally-OFF AlGaN/GaN HEMT using Delta-doped GaN cap Layer

In this paper, a normally-OFF delta (δ)-doped aluminium gallium nitride (AlGaN)/Gallium nitride (GaN) high electron mobility transistor (HEMT) for high power applications is designed and simulated in Silvaco TCAD. Normally-OFF operation is achieved by using p-GaN cap layers where SiNx is the dielectric which is placed between the gate electrode and p-GaN layer. Due to the delta (δ) doping, very low off current is achieved in the order of 10–17 A and ION/IOFF ratio in the order of 1012, which is significant enough for high power switching applications. By the use of SiNx dielectric layer, a decent threshold voltage of 2.16 V is observed. The proposed device is optimized by using various gate lengths and gate work functions.