The properties of metal-oxide semiconductor (MOS) capacitors with different chemical treatments have been examined in this study. A MOS capacitor consists of an Al2O3/n-GaN/AlN buffer/Si substrate. Four chemical treatments, containing organic solvents, oxygen plasma and BCl3 plasma, dilute acidic and alkali solvents, and hydrofluoric acid, were used to reduce the metal ions, native oxides, and organic contaminants. The n-GaN surface was treated with these chemical treatments before Al2O3 was grown on the treated n-GaN surface to reduce the interface state trap density (Dit). The value of Dit was calculated using the capacitance–voltage curve at 1 MHz. The Dit of a u-GaN surface was modified using various solutions, which further influenced the contact properties of GaN.
- Chemical treatment
- Interface state trap density