Low on-resistance and fast switching of 13-kV SiC MOSFETs with optimized junction field-effect transistor region

Abstract

In this paper, a 13-kV SiC MOSFET with a retrograde doping profile in junction field-effect transistor (JFET) regions, which were implanted by nitrogen ions with multiple energies, has been developed for power supplies of X-ray generators and electron guns with an accelerating voltage greater than 10 kV. A JFET region was optimized with device simulation to reduce on-resistance. A SiC MOSFET with an optimized JFET region was fabricated with a 5 mm × 5 mm die size. The specific on-resistance (RonA) was estimated to be 169 mΩ·cm². The blocking voltage (BVDSS) of 13.1 kV was obtained at 10 μA/cm². Owing to a low electric field in the gate oxide (Eox), a threshold voltage (Vth) shift within ± 0.06 V was achieved at the gate voltage of −15 V (equal to an electric field of −3 MV/cm) and 200 °C for 1000 hours. The dynamic test with inductive load resulted in turn-off and turn-on switching speeds of 75 kV/μs and 114 kV/μs, respectively, for the DC bus voltage of 10 kV at room temperature.