A comparison on the Electrical Characteristics of SiO₂, SiON and SiN as the Gate Insulators for the Fabrication of AlGaN/GaN Metal–Oxide/Insulator–Semiconductor High-Electron Mobility-Transistors

Abstract

We report on the effect of SiO 2 , SiN and SiON insertion for the demonstration of AlGaN/GaN metal–oxide/insulator–semiconductor high-electron mobility-transistors (MOSHEMTs/MISHEMTs) on sapphire substrates. The compositions of the three dielectrics were confirmed using X-ray photoelectron spectroscopy (XPS). All the three dielectrics showed enhanced drain saturation current density compared to unpassivated high-electron mobility-transistors (HEMTs). The SiO 2 MOSHEMTs though exhibited a very low leakage current, suffered from a relatively high degree of current collapse. The SiN MISHEMTs displayed a low drain current collapse, but, suffered from high degree of leakage current compared with other two dielectrics. SiON MOSHEMTs, taking the advantage of both SiO 2 and SiN, resulted both in low drain current collapse as well as moderate leakage current. Thus based on the improved dc characteristics, SiON proves to be a potential dielectric candidate as it simultaneously mitigates the problem of current collapse and achieves moderate leakage current.