[PO-F1] Poster Session 1

[P1-39] Development of charge-transfer type interatomic potential for SiC oxidation

^○So Takamoto¹, Takahiro Yamasaki², Takahisa Ohno², Chioko Kaneta³, Asuka Hatano¹, Satoshi Izumi¹ (1.The Univ. of Tokyo, Japan, 2.NIMS, Japan, 3.Fujitsu Lab., Japan)

Silicon carbide (SiC) is an attractive semiconductor material for applications in power electronic devices and the fabrication of a high-quality SiC/SiO₂ interface is desired. It is well known that there is a great difference in oxidation rate between the Si-face and C-face, and that the quality of oxide layer on the Si-face is better than that on the C-face. However, the atomistic mechanism of the thermal oxidation of SiC remains to be solved. In this work, we developed a new Si-C-O interatomic potential to reproduce the kinetics of the thermal oxidation of SiC. More than 1000000 properties obtained by DFT calculations were used for the fitting process. Using this interatomic potential, large-scale SiC oxidation simulations were performed. In order to focus on the reaction of O₂ molecules, the oxidation process is realized by inserting O₂ molecules into SiO₂ region. The results showed that the activation energy of the Si-face is much larger than that of the C-face. Also, the numbers of intermediate oxide states of Si atoms are in good agreement with the experimental result. In the case of the Si-face, a flat and aligned interface structure including Si¹⁺ was created. We estimated activation energies of the change of intermediate oxide states and proposed that the stability of the flat interface structure is the origin of the high activation energy of the oxidation of the Si-face. In contrast, in the case of the C-face, it is found that the Si atom at the interface are pulled up by the O atoms. This process generates the disordered interface and decreases the activation energy of the oxidation.