AlGaN/GaN/InGaN/GaN DH-HEMTs with an InGaN notch for enhanced carrier confinement

We report an AlGaN/GaN/InGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) with high-mobility two-dimensional electron gas (2-DEG) and reduced buffer leakage. The device features a 3-nm thin InxGa1-xN(x = 0.1) layer inserted into the conventional AlGaN/GaN HEMT structure. Assisted by the InGaN layers polarization field that is opposite to that in the AlGaN layer, an additional potential barrier is introduced between the 2-DEG channel and buffer, leading to enhanced carrier confinement and improved buffer isolation. For a sample grown on sapphire substrate with MOCVD-grown GaN buffer, a 2-DEG mobility of around 1300 cm(2)/V(.)s and a sheet resistance of 420 Omega/sq were obtained on this new DH-HEMT structure at room temperature. A peak transconductance of 230 mS/mm, a peak current gain cutoff frequency (f(T)) of 14.5 GHz, and a peak power gain cutoff frequency (f(max)) of 45.4 GHz were achieved on a 1 x 100 mu m device. The off-state source-drain leakage current is as low as similar to 5 mu A/mm at V-DS = 10 V For the devices on sapphire substrate, maximum power density of 3.4 W/mm and PAE of 41 % were obtained at 2 GHz.