Analysis of MOCVD SiNx Passivated N-Polar GaN MIS-HEMTs on Sapphire With High fmax.VDS,Q

This letter presents an analysis of N-polar metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with a 40 nm MOCVD SiNx passivation and a trench-gate design. A device with a 50 nm gatelength (L-g) demonstrates a 313 GHz power gain cutoff frequency (f(max)) at a quiescentdrain bias (V-DS,V- Q) of 26 V. The high f(max).V-DS,V- Q of 8.1 THz.V exhibits great potential of the device in high-frequency power applications. Investigation on small-signal parameters shows that fmax improves with V-DS,V- Q due to a reduction of gate-drain capacitance (c(gd)) and an increase of output resistance (r(ds)). When comparingwith the previously reported planar HEMT design, the shorter Lg enabled by the trench-gate design enhances the intrinsic current gain cutoff frequency (f(T, int)) leading to a higher peak f(max) at a higher V-DS,V- Q.