Improvement in Device Performance in MIS AlGaN/GaN HFETs by Designing Insulator/AlGaN/GaN Structures

摘要

To improve the device performance of GaN-based Metal-Insulator-Semiconductor (MIS) heterostructure field-effect transistors (HFETs), the layer design of MIS AlGaN/GaN HFETs has been investigated by considering the insulator/AlGaN structures as the total barrier layers of MIS HFETs. With an increased insulator thickness and decreased AlGaN thickness, where the gate capacitance is kept constant, a high transconductance was successfully obtained that was equivalent to that of HFET, in addition to the reduced gate leakage current in MIS HFETs. Channel doping design has also been proposed to incorporate into MIS HFETs to modulate the threshold voltage aiming at the same application of depression mode as conventional HFETs. In a MIS HFET with channel doping design, a significantly reduced gate leakage current was obtained with a transconductance and threshold voltage that are kept close to typical values of HFETs, indicating that the device has a potential to replace conventional HFETs.