Analysis of MOCVD SiNx Passivated N-Polar GaN MIS-HEMTs on Sapphire With High fmax\cdot 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 gate-length (Lg) demonstrates a 313 GHz power gain cutoff frequency (fmax) at a quiescent drain bias (V $_{{DS,Q}} ) of 26 V. The high fmax\cdot VDS,Q of 8.1 THz \cdot V exhibits great potential of the device in high-frequency power applications. Investigation on small-signal parameters shows that fmax improves with V $_{{DS,Q}}$ due to a reduction of gate-drain capacitance (cgd) and an increase of output resistance (rds). When comparing with 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 fmax at a higher V $_{{DS,Q}}$ . [ABSTRACT FROM PUBLISHER]