Formation of thin GaOx interlayer by thermal oxidation of SiO/GaN and its effect on electrical properties

Yamada, Takahiro*; Watanabe, Kenta*; Nozaki, Mikito*; Yoshigoe, Akitaka; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*

no journal, , 

Formation of thin GaOx interlayer by thermal oxidation of SiO/GaN structure was investigated by spectroscopic ellipsometry and synchrotron radiation photoelectron spectroscopy. In the SiO/GaN structure before thermal oxidation, GaOx interlayer (about 4 nm) was already formed. This is considered to be attributable to O plasma exposure to GaN surface during SiO deposition by plasma CVD. Thickness of the GaOx interlayer slightly increased about 1 nm by thermal oxidation up to 1000 degrees. This behavior indicates that the oxidation of GaN surface was markedly suppressed by the SiO capping layer. C-V characteristics of SiO/GaOx/GaN MOS capacitor with the thin GaOx layer, except that prepared at 1000 degrees, exhibited low frequency dispersion and hysteresis of below 10 mV. The measured C-V curves also well agreed with ideal C-V curves. These results demonstrate that the excellent GaN MOS interface properties were realized by the insertion of thin GaOx interlayer.