1. Comprehensive study on initial thermal oxidation of GaN(0001) surface and subsequent oxide growth in dry oxygen ambient.
- Author
-
Takahiro Yamada, Joyo Ito, Ryohei Asahara, Kenta Watanabe, Mikito Nozaki, Satoshi Nakazawa, Yoshiharu Anda, Masahiro Ishida, Tetsuzo Ueda, Akitaka Yoshigoe, Takuji Hosoi, Takayoshi Shimura, and Heiji Watanabe
- Subjects
ELECTRIC properties of gallium nitride ,OXIDATION ,ROUGH surfaces ,GALLIUM nitride films ,X-ray photoelectron spectroscopy ,ATOMIC force microscopy - Abstract
Initial oxidation of gallium nitride (GaN) (0001) epilayers and subsequent growth of thermal oxides in dry oxygen ambient were investigated by means of x-ray photoelectron spectroscopy, spectroscopic ellipsometry, atomic force microscopy, and x-ray diffraction measurements. It was found that initial oxide formation tends to saturate at temperatures below 800 °C, whereas the selective growth of small oxide grains proceeds at dislocations in the epilayers, followed by noticeable grain growth, leading to a rough surface morphology at higher oxidation temperatures. This indicates that oxide growth and its morphology are crucially dependent on the defect density in the GaN epilayers. Structural characterizations also reveal that polycrystalline α- and β-phase Ga
2 O3 grains in an epitaxial relation with the GaN substrate are formed from the initial stage of the oxide growth. We propose a comprehensive model for GaNoxidation mediated by nitrogen removal and mass transport and discuss the model on the basis of experimental findings. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF