Total Ionizing Dose Effects in Commercial 4H-SiC MOSFETs

This work presents a comparative analysis of total ionizing dose (TID) effects in modern commercial 4H-SiC MOSFETs, including both planar and trench-gate architectures from five manufacturers: onsemi, STMicroelectronics, Infineon, and two generations of ROHM devices. Devices rated at 650–750 V were exposed to gamma irradiation up to 500 krad using a Cobalt-60 source at gate biases of –5 V, +5 V, and +15 V, simulating space-relevant operating conditions. Threshold voltage shifts (VTH) as large as –12 V were observed in trench-gate devices, with the ROHM Gen 3 MOSFET exhibiting a VTH shift from +4.5 V to –7.5 V, converting the device to normally-on. In contrast, planar devices showed better resilience, with STMicro’s planar MOSFET maintaining VTH above +0.5 V under all test conditions and a maximum ΔVTH of only –2.5 V. Secondary effects included up to 0.5 mA of drain leakage at drain-source voltage > = 50 V and on-resistance reductions of up to 28%, correlating with increased gate overdrive. Capacitance measurements revealed gate-source capacitance increases up to 366% and decreases up to 36% in trench devices. Post-irradiation annealing up to 300 °C enabled near-complete VTH recovery in planar devices, while the trench devices showed only partial recovery, indicating deeper or more stable trap states. Extracted oxide trapped charge densities reached up to >4×10¹² cm⁻² in trench devices. These results underscore the influence of device structure, gate bias, and interface quality on radiation tolerance, with planar MOSFETs offering superior robustness for space-grade SiC power electronics.