Si epitaxial layers were selectively grown on local-oxidation-of-silicon-patterned Si (100) substrates by cold-wall ultrahigh vacuum chemical vapor deposition. The Si windows were aligned along the [110] direction on Si (100) surface. As growth temperature increased from 550 to 650degreesC, the development of (111) facets was dramatically suppressed, and the Si growth on sidewall facet planes was decreased. It is believed that surface diffusion of Si adatoms plays an important role in the morphological evolution of selective epitaxial growth (SEG). We propose a model to explain our experimental observations, and to clarify the effect of growth temperature on the facet morphology in terms of the surface mass transport and mass accumulation processes on facet surfaces. (211) facet formation between (311) and (111) facets in Si SEG is reported, and the stability of the (211) plane is also discussed. Finally, we investigated the changes in facet morphology with Si layer thickness, which supports our model for the facet evolution observed in Si SEG. (C) 2004 American Vacuum Society.