Studies on High-Voltage GaN-on-Si MIS-HEMTs Using LPCVD Si3N4as Gate Dielectric and Passivation Layer

Abstract

This paper investigates the performance of AlGaN/gallium nitride (GaN) MIS high electron mobility transistors (MIS-HEMTs). The gate dielectric layer and the surface passivation layer are formed by the low-pressure chemical vapor deposition (LPCVD) Si ₃ N ₄ . The LPCVD-Si ₃ N ₄ MIS-HEMTs exhibit a high breakdown voltage (BV) of 1162 V at I _DS = 1 μA/mm, a low OFF-state leakage of 7.7 × 10 ^-12 A/mm, and an excellent ON/OFF-current ratio of ~10 ¹¹ . Compared with the static ON-resistance of 2.88 mΩ · cm ² , the dynamic ON-resistance after high OFF-state drain bias stress at 600 V only increases to 4.89 mΩ · cm ² . The power device figure of merit = BV ² /R _ON.sp is calculated to be 469 MW · cm ^-2 . The LPCVD-Si ₃ N ₄ /GaN interface state density is in the range of (1.4-5.3) × 10 ¹³ eV ^-1 cm ^-2 extracted by the conventional conductance method. Finally, the gate insulator degradation of GaN-based MIS-HEMTs is analyzed by time-dependent dielectric breakdown test. The lifetime is extrapolated to 0.01% of failures after ten years at 300 K by fitting the data with a power law to a gate voltage of 10.1 V.