Charge Redistribution at GaN–Ga2O3 Interfaces: A Microscopic Mechanism for Low Defect Density Interfaces in Remote Plasma Processed MOS Devices Prepared on Polar GaN Faces

Interfacial defect densities, typically two orders of magnitude lower than those usually obtained at [III–V]-dielectric interfaces, have been demonstrated for GaN capacitors and field effect transistors (FETs). Separate and independently controlled interface formation and film deposition by remote plasma-assisted processing steps performed at 300 °C were employed. The interfacial oxide is Ga2O3, and the deposited gate dielectric is SiO2. Models for the chemical bonding at the GaN–Ga2O3 interface and at the internal dielectric Ga2O3–SiO2 are presented. The most important aspect of the interface formation involves a redistribution of electrons in the surface atom dangling bonds of the GaN polar face that promotes formation of two-electron bonds with the interfacial dielectric.