Carbonization of Si surfaces was performed using C-saturated CO gas. The experimental conditions were determined by considering the phase stability diagram for the SiC-SiO2-CO system constructed using thermodynamic data. Annealing Si substrates under the SiC-stable condition led to the formation of SiC over the entire surfaces of Si(100), Si(110), and Si(111) substrates. During carbonization, SiC nuclei first form on the Si surface. These nuclei advances grow through the surface diffusion of Si atoms, which leads to poor in-plane uniformity of the amount of SiC and the formation of numerous voids in a similar manner to that observed for other C sources. (C) 2015 Elsevier B.V. All rights reserved.