. Synchrotron radiation with surface X-ray diffraction is conducted to study pyrite FeS2 films on Si (10 0) wafers. The results show that the strong (2 0 0) reflection for the FeS2/Si(1 0 0) sample primarily comes from the stress peak of the silicon substrate, other than the effect of the preferred orientation of pyrite crystal grains which has been assumed previously. On the contrary, the FeS2/Si(1 0 0) sample actually indicates a strong preferred growth along (3 1 1) orientation, and this preferential growth of pyrite films becomes intenser with the prolonged annealing time. (C) 2004 Elsevier B.V. All rights reserved.