Normally OFF GaN-on-Si MIS-HEMTs Fabricated With LPCVD-SiNx Passivation and High-Temperature Gate Recess

Abstract

Low-current-collapse normally OFF GaN-on-Si MIS high-electron-mobility transistors (MIS-HEMTs) are fabricated with low-pressure chemical-vapor-deposited SiN x (LPCVD-SiN x ) passivation and high-temperature low-damage gate-recess technique. The high-thermal-stability LPCVD-SiN x enables a passivation-prior-to-ohmic process strategy and effectively suppresses deep states at the passivation/HEMT interface. The fabricated MIS-HEMTs feature a high $V_{\rm {TH}} $ of +0.85 V at the drain current of 1 $\mu $ A/mm and a remarkable ON/OFF current ratio of 1010 while reduced dynamic ON-resistance as compared to plasma-enhanced chemical-vapor-deposited SiO2 passivation. High field-effect channel mobility of 180 cm $^{2}/ \text{V} \cdot \text{s} $ is achieved, leading to a high maximum drain current density of 663 mA/mm.