Above 2000 V breakdown voltage at 600 K GaN-on-silicon high electron mobility transistors

We report a three-terminal breakdown voltage over 3 kV on AlGaN/GaN high electron mobility transistors (HEMTs) grown on 6-in. silicon (111) substrate with a buffer thickness of 5.5 μm. A local substrate removal all around the drain of the transistors has been developed in order to suppress the parasitic substrate conduction, which enables improving the device breakdown voltage by more than 200%. This establishes a new record breakdown voltage for GaN-on-silicon lateral power devices while maintaining a low-specific on-resistance of about 10 m Ω cm2. Furthermore, the device performance has been investigated at elevated temperature up to 600 K under high vacuum. Breakdown voltages well above 2 kV at temperatures exceeding 300 °C have been achieved for the first time owing to the suppression of the buffer layer/Silicon substrate parasitic conduction. These data demonstrates that the local substrate removal is not only an efficient solution to significantly boost the device breakdown voltage but also allows improving the high voltage operation under high temperature, which is a key feature for high power electronic applications.