Fabrication of AlGaN/GaN-double-insulator metal-oxide-semiconductor high-electron-mobility transistors using SO2 and SiN as gate insulators

We report on the fabrication of AlGaN/GaN double-insulator MOSHEMTs using SiO2 and SiN as the prime gate insulators. Both the dielectrics showed enhanced saturation current density and pinch-off voltage compared to conventional HEMTs. SiO2/SiN/AlGaN/GaN MOSHEMTs exhibited a low current collapse and low leakage current compared to SiN MISHEMTs and unpassivated HEMTs. However, the SiN/SiO2/AlGaN/GaN MOSHEMTs exhibited a lower current collapse coupled with moderate leakage current compared to SiO2 MOSHEMTs and unpassivated HEMTs. The comparison of device dc characteristics of double-insulator MOSHEMTs with single-insulator MOSHEMTs revealed its superiority in reducing the problem of current collapse and leakage current simultaneously. (c) 2005 WILEY-VCH Verlag GmbH & Co.