Bias dependent microwave performance of AlGaN/GaN MODFET's up to 100 V

1-mu m gate-length AlGaN/GaN modulation doped field effect transistors (MODFET's) have been fabricated on an insulating GaN buffer layer for better carrier confinement, These devices demonstrate simultaneously high current levels (>500 mA/mm), excellent pinch-off and high gate-drain breakdown voltages (220 V for 3 mu m gate-drain spacing), In contrast to their GaAs counterparts, the current-gain cutoff frequency of the AlGaN/GaN devices shows little degradation at high drain voltage biases, A power-gain cutoff frequency of 19 GHz is obtained at 100 V, ACW power density of 1.57 W/mm at 4 Ghz is also achieved when biased at 28 V and 205 mA/mm.