GaN HEMTs and MOSHEMTs for Power Switching Applications

GaN based high electron mobility transistors (HEMT) are among the most promising semiconductor devices for future high frequency, high efficiency power switching applications due to unique material properties of GaN, featuring wide band gap (3.4 eV), high critical electric field (> 3 MV/cm) and high electron saturation velocity. While the material and device physics for GaN HEMTs have been studied extensively in the past decades, penetration of power device market relies on the development of high performance devices, which requires solving a series of critical issues including gate leakage, device passivation and threshold voltage control. In this work, development of enhancement mode GaN HEMTs and MOSHEMTs is discussed, with a focus on variation of device fabrication techniques and its impact on device characteristics, providing solutions to the aforementioned issues. Experimentally, high performance GaN MOSHEMTs with the lattice matched In0.17Al0.83N barriers are demonstrated, which show comparable metrics to the state-of-the-art devices in terms of switching frequency and power density.