Review of Ultra Wide Bandgap (UWBG) GaN Based HEMTs: Opportunities for high efficiency power conversion in renewable energy and electric vehicle applications

The rising demand for efficient, compact, and high performance power electronic systems in renewable energy and electric vehicle (EV) applications has accelerated the transition from traditional silicon based devices to wide bandgap (WBG) and ultra wide bandgap (UWBG) semiconductors. Among these, gallium nitride (GaN) based high electron mobility transistors (HEMTs) have emerged as a transformative technology due to their superior electrical and thermal properties, including high breakdown voltage, low on resistance, and high frequency operation. This review provides a comprehensive analysis of UWBG GaN based HEMTs, focusing on their material fundamentals, device architectures, and recent advances in fabrication techniques and thermal management. The paper explores their practical deployment in renewable energy systems such as solar inverters and wind power converters, as well as in EV applications including traction inverters and on board chargers. A comparative performance analysis is presented to benchmark UWBG GaN HEMTs against traditional Si, SiC, and conventional GaN technologies. Additionally, the paper highlights the challenges related to material defects, fabrication cost, and long term reliability, concluding with a call for further experimental and system level studies. The findings underscore UWBG GaN HEMTs as promising candidates for next generation power electronics, offering the potential for significant efficiency gains and system level innovation.