Superior DC and RF Performance of AlGaN-Channel HEMT at High Temperatures

properties of AIGaN-channel HEMT fabricated on a free-standing A1N substrate, estimated at temperatures between 25 and 300°C. The AIGaNchannel HEMT exhibited significantly reduced temperature dependence in DC and RF device characteristics, as compared to those for the conventional A1GaN/GaN HEMT, resulting in larger values in both saturated drain current and current gain cutoff frequency at 300°C. Delay time analyses suggested that the temperature dependence of the AIGaN-channel HEMT was primarily dominated by the effective electron velocity in the A1GaN channel. These results indicate that an A1GaN-channel HEMT fabricated on an AIN substrate is promising for high-performance device applications at high temperatures. key words: AlGaN channel, high temperature, HEMT was still larger for the conventional A1GaN/GaN HEMT than that for the A1GaN-channel device, and no data have been reported on the high-temperature RF performance for the AlGaN-channel HEMT. In this paper, DC and RF performance of A1GaNchannel HEMTs fabricated on an A1N substrate is presented. The maximum drain current and the current gain cutoff frequency measured at temperatures from RT to 300°C are compared between devices with an AIGaN channel and a GaN channel. The mechanism responsible for the superior performance for the developed A1GaN-channel HEMT at high temperatures is discussed.