Microwave operation of GaN/AlGaN-doped channel heterostructure field effect transistors

Abstract

We report on the microwave operation of 1 μm gate AlGaN/GaN doped channel heterostructure field effect transistors (DC-HFET's) with the cutoff frequency f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> of 18.3 GHz. These devices exhibit the cutoff frequency-gate length product in excess of 18 GHz/spl middot/μm, comparable to that of the state-of-the-art GaAs MESFET's. We explain these improvements in the device performance by the increased sheet carrier density in the device channel and by a reduction in the parasitic series resistances, caused by doping the device channel.