High-frequency measurements of AlGaN/GaN HEMTs at high temperatures

High-frequency measurements of the 1.3-μm-long gate AlGaN-GaN HEMTs have been performed at temperatures ranging from 23 to 187/spl deg/C. The cutoff frequency f
_T
decreased with increasing temperature. It was 13.7 and 8.7 GHz at 23 and 187/spl deg/C, respectively. The effective electron velocities /spl upsi//sub eff/ in the channel evaluated from the total delay time versus I/sub D/-inverse relation were 1.2 and 0.8×10/sup 7/ cm/s at 23 and 187/spl deg/C, respectively.