Low-Temperature ICP-CVD SiNx as Gate Dielectric for GaN-Based MIS-HEMTs

SiN_x deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) technique at low temperature (70 °C) was investigated as gate dielectric for AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). Besides significant reduction in gate leakage current, the MIS-HEMTs showed improvement in drain current characteristics, 2DEG channel mobility, I_ON/I_OFF ratio, ON-resistance, and three terminal breakdown voltage as compared with reference HEMTs. Very small capacitance-voltage hysteresis (~68 mV) was observed for a gate swing of -10 to +5 V. The effect of SiN_x thickness (t_SiNx) on the characteristics of MIS-HEMTs was studied. The performance of fabricated MIS-HEMTs was found to be stable for a wide range of temperature.