AlGaN/GaN/InGaN/GaN HEMTs with an InGaN‐notch

Abstract

AbstractWe report an AlGaN/GaN/InGaN/GaN double heterojunction HEMT (DH‐HEMT) with reduced buffer leakage and high‐mobility two‐dimensional‐electron‐gas (2DEG). A 3‐nm thin InxGa1–xN (x = 0.1) layer was inserted into the conventional AlGaN/GaN HEMT structure. A 2DEG mobility of around 1300 cm2/Vs and a sheet resistance of 480 Ω/sq were obtained at room temperature on this new DH‐HEMT structure grown on sapphire substrate with MOCVD‐grown GaN buffer. A peak transconductance of 230 mS/mm, a peak current gain cutoff frequency (fT ) of 14.5 GHz, and a peak power gain cutoff frequency (fmax ) of 45.4 GHz were achieved on a 1×100 μm device. The off‐state source‐drain leakage current is as low as ∼5 μA/mm at VDS = 10 V and the gate leakage current is about 10 μA/mm at a reverse bias of 20 V. For the devices on sapphire substrate, maximum power density of 3.4 W/mm and PAE of 41% were obtained at 2 GHz. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)