Background: The escalating demand for high-efficiency power conversion in electric vehicle (EV) on-board chargers, photovoltaic inverters, and data centre power supplies has driven transition from silicon (Si) to wide-bandgap semiconductor devices. Gallium nitride (GaN) high electron mobility transistors (HEMTs) offer superior figure-of-merit compared to Si MOSFETs through higher critical electric field (3.3 MV/cm), higher electron mobility (2000 cm²/V·s), and lower on-resistance, enabling higher switching frequencies with reduced switching losses. Objective: To experimentally characterise the switching performance, thermal behaviour, and gate drive requirements of AlGaN/GaN HEMTs in a 600 V/10 A half-bridge converter topology and compare against Si MOSFET and SiC MOSFET benchmarks. Methods: Double-pulse test (DPT) circuits were designed and fabricated for switching loss characterisation at 400 V DC bus voltage. Thermal resistance was measured using structure function analysis. Gate drive optimisation was performed by varying gate resistance Rg (2.2–22 Ω) and gate voltage swing (−3V/+6V and 0V/+6V). Custom gate driver ICs (Texas Instruments LMG1020) were evaluated for propagation delay and cross-conduction prevention. Results: GaN HEMT achieved total switching loss of 18.4 µJ at 400 V, 10 A — 74% reduction versus Si MOSFET (71.2 µJ) and 52% reduction versus SiC MOSFET (38.4 µJ). Converter efficiency at 100 kHz reached 98.2% (GaN), 96.4% (SiC), and 94.1% (Si). Thermal resistance junction-to-case was 0.8°C/W for GaN-on-SiC versus 1.6°C/W for GaN-on-Si. Conclusion: AlGaN/GaN HEMTs deliver compelling switching and efficiency advantages over Si and SiC technologies at frequencies above 50 kHz, with gate drive design being the critical enabling factor for reliable high-frequency operation.
Vikram Singh, Neha Agarwal, Sanjay Verma, Anupam Das (Thu,) studied this question.