Fixed polarizer, rotating polarizer and fixed analyzer variable angle spectroscopic ellipsometry was used to determine the optical properties of implanted Si nanocrystals obtained by implantation of Si+ ions into thermally grown SiO2 layers on c-Si substrate. Ellipsometric measurements on the implanted samples were performed in air at room temperature at angles of incidence of 50, 60, 65, 67 and 70degrees. The values of layer thickness, optical indices of nc-Si, and volume fractions of components were extracted using multilayer analysis by combining the Bruggeman effective medium approximation with the Fourouhi-Bloomer model, and by taking into account the distribution of implanted ions in the optical model. The dependence of complex refractive index of Si nanocrystals on the growth temperature were discussed. (C) 2003 Elsevier B.V. All rights reserved.