Al2O3 films were deposited on thermally oxidized Si(1 0 0) substrates by ion beam enhanced deposition (IBED), and then implanted with 120 keV Er ions. A thermal anneal at 773-1273 K in Ar environment was performed for 1 h for each sample studied. Photoluminescence and optical transmission spectra of all samples were measured with optical spectrometer Nicolet 860. Annealed at 973 K, the pump absorption cross-section reaches its minimum value which lead to the appearance of the lowest PL intensity and 1140 nm spectrum. Optical transmission spectra indicate that the pump absorption cross-section relates to the minimum optical absorption of the Al2O3 materials. (C) 2003 Elsevier B.V. All rights reserved.