AlGaN/GaN MIS-HEMTs of Very-Low ${V}_{\sf {{th}}}$ Hysteresis and Current Collapse With In-Situ Pre-Deposition Plasma Nitridation and LPCVD-Si3N4 Gate Insulator

In this letter, we report an in-situ predeposition plasma nitridation process, which is adopted to remove the GaN surface oxygen-related bonds and reduce surface dangling bonds by forming Ga-N bonds prior to the low-pressure chemical vapor deposition (LPCVD)Si
₃
N
₄
deposition. It demonstrates that the Vth hysteresis and current collapse of the device were dramatically improved due to high-quality LPCVD-Si
₃
N
₄
/GaN interface. The MIS-HEMTs using this in-situ pre-deposition plasma nitridation exhibit a very-low Vth hysteresis of 186 mV at VG-sweep = (-30 V, +24 V), a high breakdown voltage of 881 V with the substrate grounded. Meanwhile, the MIS-HEMT dynamic RON is only 18% larger than the static RON after OFF-state VDS stress of 600 V (the OFF to ON switching time interval is set to 200 μs).