Uniformity and high temperature performance of X-band nitride power HEMTs fabricated from 2-inch epitaxy

X-band performance, high temperature D.C. operation and uniformity have been evaluated for 1 μm gate AlGaN/GaN HEMTs grown by RF atomic nitrogen plasma MBE. Deposition and fabrication were performed on 2-inch (0001) sapphire substrates to determine process uniformity. HEMTs with 300 μm total gate width and dual gate finger geometry have been fabricated with 650–700 cm² V^?1×s mobility. Maximum frequency cut-offs on the order of 8–10 GHz were achieved. D.C. performance at room temperature was >500 mA mm^?1, and external transconductance was >70 mS mm^?1. The transistors operated at test temperatures of 425°C in air.