摘要： Power conversion losses are pervasive in all areas of electricity consumption, including motion control, lighting, air conditioning, and computation technology. To minimize losses, high efficiency switches are required for the fundamental power conversion units (motors, inverters, and generators) that drive the components. The workhorse of this industry has been silicon-based power switches, but that technology has matured to the fundamental material limits. As a wide bandgap semiconductor, the GaN materials system represents a critical technology for next-generation electronics in many applications due to the high breakdown field, high mobility, and chemical and thermal stability. Devices based on GaN are already well-known to many of us and are used in our daily lives, primarily as the core technology behind solid state lighting based on the GaN light emitting diode (LED), for which Nakamura, Amano, and Akasaki won the Nobel Prize in 2014. In addition GaN-based high electron mobility transistors (HEMTs) have been widely commercialized as RF power amplifiers for communications and radar applications. However, GaN-based devices are relatively nascent in the power conversion field, as most device technology has been dominated by Si and, recently, SiC. Power devices have unique requirements, such as normally-off behavior for fail-safe operation and high field management for high voltage operation, that have proven notoriously difficult in this system, thus an extension of HEMT designs and processing knowledge is not possible.