Photoluminescence from ion-beam cosputtered Si/SiO2 thin films

We report the observation of visible and stable room temperature photoluminescence (PL) from thin composite Si/SiO2 films deposited onto various substrates (Si, SiO2, Al and C) by means of an ion-beam sputtering system. Transmission electron microscopy (TEM) observations of the films deposited on carbon substrates reveal the presence of filamentary structures, with nanometric dimensions, of crystalline silicon embedded in an amorphous matrix. While changes of film composition do not influence the main features of the FL, we found that the PL shape and intensity is strongly dependent on the nature of the substrate. The necessary combination of Si and SiO2 for producing the light-emitting material and the TEM results suggest that quantum confinement of carriers in the silicon nanocrystals is a possible origin of the observed FL. Copyright (C) 1996 Elsevier Science Lt