Gallium Nitride Power HEMT Switching Performance, Reliability, and Loss Benchmarking Against SiC MOSFETs for 650 V-Class DC-DC Converter Applications

This study investigates switching performance, thermal reliability, and converter efficiency benchmarking of 650 V GaN e-HEMT devices versus SiC MOSFETs in a 500 kHz hard-switched DC-DC converter topology within the context of power electronics and wide bandgap semiconductor engineering, an area of growing scientific importance given its implications for high-frequency DC-DC conversion for data center power delivery, EV on-board charging, and photovoltaic microinverters. Using double-pulse switching energy measurement, converter efficiency measurement via precision power analyzer, and 1,000-hour accelerated reliability testing at 125 C junction temperature, we examine GaN HEMT lateral 2DEG channel and zero reverse recovery enabling 3-5x lower switching energy than SiC at 650 V class, enabling efficiency advantage to emerge above 200 kHz switching frequency where switching loss dominates in 12 device variants (4 GaN + 4 SiC + 4 Si reference) tested at 8 switching frequencies (50-1,000 kHz) with 1,000-hour AHT on 48 devices (4 devices x 12 variants) drawn from power electronics test bench at 400 V bus, 500 W, 50% duty cycle with Pearson coil current and high-voltage differential voltage probes. Results indicate that GaN e-HEMT achieves 98.8% peak converter efficiency at 500 kHz versus 97.8% for SiC MOSFET (1.0 pp advantage) with 3.2x lower switching energy (Eon+Eoff = 4.8 vs. 15.4 uJ) enabling 2.4x higher power density at equivalent thermal management (p < 0.001), with 98.8% GaN vs. 97.8% SiC peak efficiency; 3.2x lower switching energy; 2.4x power density advantage as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to power electronics and wide bandgap semiconductor engineering and carry actionable implications for the design of programs and policies targeting high-frequency DC-DC conversion for data center power delivery, EV on-board charging, and photovoltaic microinverters.