[TuP3C] Power Devices

[TuP3C-11] Mist Thermal Oxidation on Si and GaN Surfaces Using Mist-CVD Method

〇Thin Nu Soe¹, Ryosuke Hamasuna¹, Takumi Hirakura¹, Yusui Nakamura¹, Zenji Yatabe² (1. Kumamoto Univ. (Japan), 2. Hokkaido Univ. (Japan))

In this study, mist-CVD is used for mist thermal oxidation of GaN surface to investigate its applicability as a surface oxidation process for GaN-based devices. In addition, the oxidation mechanism in the mist-CVD process was analyzed by applying the Deal–Grove model to thermally grown SiO₂ formed in mist ambient. Mist thermal oxidation was performed on p-type Si and GaN-on-sapphire surfaces by using ultrasonically atomized deionized water as the oxidizing agent. The mist-oxidized SiO₂ on Si exhibited a mass density comparable to conventional thermally oxidized SiO₂, and a relatively high breakdown electric field of approximately 8 MV/cm. The mist-oxidation of GaN surface at 1000°C resulted in the formation of polycrystalline Ga₂O₃ phase with a mass density of 5.2 g/cm³. These results suggest that high-quality oxidized films can be produced with mist thermal oxidation. Furthermore, kinetic analysis using the Deal–Grove model revealed that the initial growth behavior of mist thermal oxidation is similar to the linear growth characteristics of wet oxidation.