High power In0.49Ga0.51P/In0.15Ga0.85As heterostructure doped-channel FETs

A high barrier Schottky gate on InGaP/InGaAs doped-channel FETs (DCFETs) pr ovides a high current density, high gate-to-drain breakdown voltage and a b etter linear operation over a wide gate bias range. However, these doped-ch annel devices are limited by a large parasitic resistance associated with a 20 nm thick undoped InGaP layer beneath the gate metal. In this study, we inserted a Si delta -doped layer inside this high bandgap undoped InGaP lay er to reduce parasitic resistances and to enhance device DC and RF power pe rformance. These modified DCFETs (M-DCFETs) demonstrated an output power de nsity of 204 mW/mm, a power-added efficiency of 45%, and a linear power gai n of 18.3 dB for an 1 mm gate-width device under a 2.4 GHz operation. These characteristics suggest that doped-channel FETs with a Si delta -doped lay er provide a good potential for high power microwave device applications.