A blue photoluminescence band centered at 440 nm was observed from Si-Ge-SiO 2 co-sputtered films at room temperature. This band gains intensity after the film was annealed at a temperature around 900°C in N 2 atmosphere. From analysis of photoluminescence excitation, Raman and X-ray photoelectron spectra, it turns out that the luminescence is probably from some interfacial state between Si 1 - x Ge x nanoparticles and the SiO 2 matrix.