GaN MOSFETs with Large Current and Normally-Off Operation

摘要

GaN is promising for high-power, high-temperature devices due to its large bandgap, high critical electric field, and high saturation velocity compared with Si and SiC. The MOSFET structure can be operated at a positive threshold voltage, namely the normally-off mode, which is preferable for power transistors in terms of failsafe operation. In order to realize MOSFET operation, good interface quality at SiO{sub}2/GaN and low resistance in the n+-contact layer is strongly required. We have overcome these requirements by precise thermal control. Finally, we have fabricated GaN MOSFETs and have achieved more than 1 A operation in the normally-off mode at more than 250°C. The breakdown voltage was more than 1500 V.