Ab Initio Study of Growth Mechanism of 4H–SiC: Adsorption and Surface Reaction of C2H2, C2H4, CH4, and CH3

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• 作者：Pitsiri SukkaewÖrjan Danielsson ; Olof Kordina ; Erik Janzén ; Lars Ojamäe
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 19, 2017
• 年：2017
• 卷：121
• 期：2
• 页码：1249-1256
• 全文大小：450K
• ISSN：1932-7455

文摘

Silicon carbide is a semiconductor material with ideal properties for high-temperature and high-power applications. The epitaxial layer fabrication is usually performed using chemical vapor deposition (CVD) under a hydrogen rich atmosphere and high temperature. At such conditions the surface of the growing layer is expected to be passivated by the abundantly present hydrogen. In this work, we use quantum chemical density functional theory (B3LYP and M06-2X) and transition state theory to study surface reactions related to the deposition of carbon on the (0001) surface of 4H–SiC. We show that it is unlikely for an adsorption to occur on a passivated site unless the hydrogen termination is removed. We propose that unterminated sites can be effectively created during the CVD by an abstraction process. We provide details of the adsorption process of active carbon species, namely CH<sub>3sub>, CH<sub>4sub>, C<sub>2sub>H<sub>2sub>, and C<sub>2sub>H<sub>4sub> gases, and their subsequent surface reactions such as desorption, abstraction of neighboring surface hydrogens and dimer formation. The reaction rates and sticking coefficients are provided for the temperature range of 298–2500 K. Finally, entire reaction paths from adsorptions to stable surface products are presented and discussed.