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 passivatecl,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 CH3, CH4, C2H2, and C2H4 gases, and their subsequent surface reactions such as desorption, abstraction of neighboring surface, hydrogens and dinner 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.
Funding Agencies|Swedish Foundation for Strategic Research; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM); Linkoping University