The core structure and growth process of stacking-fault tetrahedron (SET) in Si film growth are investigated, by adopting the Cl-adsorbed Si(111) surfaces and using molecular dynamics (MD) simulation based on empirical interatomic interactions. It was shown that most Cl atoms on the substrate diffuse onto the surface and the defects barely appear. However, when more than one Cl atoms aggregate on the Si(111) substrate, the dome structure of Si atoms covering the Cl atoms is produced and it grows into a stacking-fault tetrahedron. These theoretical results are in agreement with recent observations. (C) 2004 Elsevier B.V. All rights reserved.