Co-deposition of Si and CH4 gas on a Si(111) surface at different temperatures is studied by reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). For comparison, Si deposition on Si(111) and exposure of a Si surface to CH4 are also investigated. From RHEED patterns, it is found that a SiC layer was only obtained by exposing Si to 1.8 X 10(4) L of CH4 at 800 degrees C. The AFM images corresponding to RHEED results show that the step width of the clean 7 x 7 surface is similar to that of SiC grown at 800 degrees C, while the step width of 3D-Si grown by co-deposition of Si and CH4 at 600 degrees C is about five times wider. It is considered that the presence of CH4 in the co-deposition with Si enhances the step width on the surface. Triangular Si islands with average size about 30 nm are observed at the terrace region in the co-deposition case, while in the case of CH4 deposition, circular shaped SiC islands with an average size of 10 nm are observed. (c) 2006 Elsevier B.V. All rights reserved.