Submicron-gate InP power MISFET's with improved output power density at 18 and 20 GHz

The microwave characteristics at 18 and 20 GHz of submicron-gate indium phosphide (InP) metal-insulator-semiconductor field-effect transistors (MISFETs) for high output power density applications are presented. InP power MISFETs were fabricated with 0.7 mu m gate lengths, 0.2 mm gate widths, and drain-source spacings of 2, 3 and 5 mu m. The output power density was investigated as a function of drain-source spacing. The best output power density and gain were obtained for drain-source spacings of 3 mu m. At 18 GHz output power densities of 1.59 W/mm with a gain of 3.47 dB and a power-added efficiency of 20.0% were obtained for a drain-source spacing of 3 mu m. At 20 GHz output power densities of 1.20 W/mm with a gain of 3.17 dB and a power-added efficiency of 13.6% were obtained for a drain-source spacing of 3 mu m. >