High power In_0.49Ga_0.51P/In_0.15Ga_0.85As heterostructure doped-channel FETs

A high barrier Schottky gate on InGaP/InGaAs doped-channel FETs (DCFETs) provides a high current density, high gate-to-drain breakdown voltage and a better linear operation over a wide gate bias range. However, these doped-channel 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 δ-doped layer inside this high bandgap undoped InGap layer to reduce parasitic resistances and to enhance device DC and RF power performance. These modified DCFETs (M-DCFETs) demonstrated an output power density of 204 mW/mm, a power-added efficiency of 45%, and a linear power gain 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 δ-doped layer provide a good potential for high power microwave device applications.