GaN based high electron mobility transistors for microwave and RF control applications

Heterojunction field-effect transistors (HFETs) or high-electron mobility transistors (HEMTs) based on Al/sub x/Ga/sub 1-x/N/GaN are studied for their use as control components for high-power microwave and RF control devices (switches, phase-shifters, etc.). A linear operation model was developed for these components so that optimum transistor geometry and operation parameters may be determined for their use in this application. It was experimentally established that the HFET resistance is low for voltages of +1.0 volts, and that the capacitive reactance increases for DC gate voltages below the threshold voltage of approximately -1.5 volts.