High-speed AlGaN/GaN HFETs fabricated by wet etching mesa isolation
The authors demonstrate high-performance AlGaN/GaN heterostructure field-effect transistors (HFETs) with mesa isolation achieved by a recently developed UV-assisted, batch processing compatible, wet etching process. HFETs with a 0.2 µm gate feature peak cutoff frequencies of fT = 43 GHz and fMAX = 98 GHz for a piezoelectric HFET grown on a sapphire substrate by molecular beam epitaxy. The transistors feature low gate diode leakage currents and display no sensitivity to visible light.