AlGaN/GaN MISHFET: A novel alternative to power HFETs for high temperature microwave digital and switching applications

We report high temperature microwave characteristics of AlGaN/GaN MISHFET and present comparative studies of this device with regular HFET structures. The effect of various temperature dependent material parameters are taken into account to evaluate the small signal parameters for wide temperature (25degC < T < 300degC) range. The effect of piezoelectric and spontaneous polarization has also been considered. Our AlGaN/GaN MISHFET structure demonstrates larger drain currents, cut-off frequency and better saturation characteristics at high temperatures. Microwave saturation output power for MISHFET is obtained as 3.8 W/mm relative to 1.4 W/mm for HFET at 300degC.