First-principles and thermodynamic analysis for gas phase reactions and structures of the SiC(0001) surface under conventional CVD and Halide CVD environments

The halide chemical vapor deposition (HCVD) technique has been improved to realize the defect-free 4H-SiC epitaxial layers. Although it is possible to obtain the 4H-SiC epitaxial layers by both HCVD and conventional CVD techniques, it has not been clarified what effects halide gases have on the growth mechanisms, especially for the surface reactions. We have performed the first-principles calculations and thermodynamics analysis to reveal the gas phase reactions and surface structures under the conventional CVD and HCVD environments. The silicon clusters and Si2C gases are the main products under the conventional CVD environments, while it changes to the SiCl2 gas under the HCVD environments. Moreover, we have clarified that the adsorption of Si gases onto the surface is suppressed under the HCVD environments. These results indicate that the introduction of halide gas can suppress the clustering of silicon both in the gas phase and on the surface.