The thickness dependent stripe structure stabilization of Ag films on Si(I 1 1)-(4 x I)-In substrate is thermodynamically considered. It is found that for the stability of the structure, there is a competition between the sum of elastic energy and stacking fault energy in the film and the film-substrate interface energy. The presence of equilibrium of them leads to a critical film thickness. Beyond it, the stripe structure will transform into a flat one. Our prediction for n(c), of Ag films shows reasonable agreement with experimental data. In addition, according to the established model, it is predicted that An could also form the above stripe structure on this substrate with a similar n(c) value of Ag. (c) 2006 Elsevier B.V. All rights reserved.