Optical characteristics of Si/SiO2 multilayers prepared by magnetron sputtering

Si/SiO2 multilayers have been successfully prepared by magnetron sputtering and subsequently thermal annealed in an Ar atmosphere at a temperature of more than 500 °C. The surface of the as-deposited films is compact and smooth, and the distribution of grain size estimated to be 20 nm is uniform. For Si/SiO2 multilayers annealed at 1100 °C, the Si sublayer sandwiched between potential barrier SiO2 is crystalline structure by means of the analysis of Raman spectra and XRD data. The visible PL peak accompanying to a blue-shift with the decrease of Si sublayer thickness has been observed, and the intensity of this peak enhances with the increase of annealing temperature. The visible luminescence properties of Si/SiO2 multilayers can be ascribed to quantum confinement of electron–hole pairs in quantum wells with grain size lower than 4.5 nm. In Si/SiO2 multilayers, not only quantum confinement but also Si–SiO2 interface states play an important role in the optical transition. The PL peak located at 779 nm is independent of the thickness of Si sublayer, so it may be ascribed to interface mediated transition. Typical Si dangling bonds defect could be a dominating obstacle to high luminescence efficiencies.