Dependence of DC and RF characteristics on gatelength for high currentAlGaN/GaN HFETs

The fabrication and performance of AlGaN/GaN heterostructure field-effect transistors of various gate lengths are reported. The unity current gain cutoff frequency (ft), maximum frequency of oscillation (fmax), and threshold voltage are investigated against gate length. The measured ft and fmax values ranged from 37 and 81 GHz to 11 and 31 GHz for the 0.25 and 1 µm gate length devices, respectively. These devices also exhibited drain currents as high as 1 A/mm.