X‐ray photoelectron spectroscopy and atomic force microscopy are employed in the characterization of the first stages in the growth of carbon layers on a (001) Si substrate which is not scratched with diamond powder before placing it in an Ar–2%CH4–H2plasma discharge. Results show that the first layers could be formed in SiC grains where the carbon diamond particles nucleate. The high nucleation density of 1.109–5.109nuclei. cm−2and the low aggregates density lead to a smooth surface. ©1996 American Institute of Physics.