AlGaN Channel High Electron Mobility Transistors with an AlxGa1-xN/GaN Composite Buffer Layer

We report an AlGaN channel high electron mobility transistor(HEMT) on a sapphire substrate with a 1000-nm AlxGa1-xN(x = 0-0.18)/GaN composite buffer layer.With a significant improvement of crystal quality,the device features a high product of ns·μn.The AlGaN channel HEMTs presented show improved performance with respect to the conventional AlGaN channel HEMTs,including the on-resistance reduced from 31.2 to 8.1 Ω·mm,saturation drain current at 2 V gate bias promoted from 218 to 540mA/mm,peak transconductance at 10 V drain bias promoted from 100 to a state-of-the-art value of 174mS/mm,and reverse gate leakage current reduced from1.85 × 10-3to 2.15 × 10-5mA/mm at VGD=-20 V.