Device characteristics of the GaN/InGaN-doped channel HFETs

First dc, small signal, and RF power characteristics of GaN/InGaN doped-channel heterojunction field effect transistors (HFETs) are reported. HFETs with a 1-μm gate length have demonstrated a maximum drain current of 272 mA/mm, a flat G/sub m/ around 65 mS/mm in a V/sub GS/ between -0.65 V and +2.0 V, and an on-state breakdown voltage over 50 V. Complete pinchoff was observed for a -3.5 V gate bias. Devices with a 1-μm gate length have exhibited an f
_T
of 8 GHz and f
_max
of 20 GHz. A saturated output power of 26 dBm was obtained at 1.9 GHz for a 1 μm×1 mm device.