Effects of an n⁻layer under the gate on the performance of InP MESFET's

The microwave and dc performance of Schottky barrier InP FET's where an n-layer of low carrier concentration is incorporated between the gate metal and the active layer are reported. FET's having gate dimensions of 1 µm × 200 µm and a channel length of 7 µm were fabricated. The observed gate leakage current was about 1 µA at a reverse bias of -12 V. The voltage that can be applied to the drain before breakdown was about +20 V while the gate bias was kept at -5 V. A maximum available gain of 6 dB in a microstrip circuit was measured at 9 GHz.