Alternately Er-doped Si-rich Al2O3 multilayer film, which consists of 20 layers of alternate Er-Si-codoped Al2O3 and Si-doped Al2O3 layers, has been synthesized by magnetron cosputtering. The structural and optical properties of the multilayer film as a function of annealing temperature in the range of 700-1100 degrees C were studied by Raman, X-ray diffraction, high-resolution transmission electron microscopy and photoluminescence (PL). The results show that Si atoms in the multilayer film cluster and have been crystallized gradually into Si nanocrystals with increasing annealing temperature to 950 degrees C. Upon annealing above 950 degrees C, however, the Er2O3 and Er4Al2O9 phases have been formed, resulting in a rapid decrease of PL intensity. It is necessary to control the size and spatial distributions of Si-NCs and optically activate Er3+ ions in order to improve PL response. (C) 2010 Elsevier B.V. All rights reserved.