Ellipsometric spectroscopy study of photoluminescent Si/SiO2 systems obtained by magnetron co-sputtering

Si nanograins embedded in silica matrix were obtained by magnetron cosputte ring of both Si and SiO2 at different substrate temperature (200-700 degree s C) and thermal annealing at 1100 degrees C. The samples were characterize d by ellipsometric spectroscopy, high-resolution electron microscopy observ ations and photoluminescence. The highest excess of Si atoms was found to b e incorporated for deposition temperature near 400-500 degrees C, giving ri se to a maximum PL and a shift of the peak position towards lower energy. T hese features might be interpreted in terms of quantum size effects and of density of grains, even though the interface states seem to be involved in the improvement of the photoluminescence efficiency. (C) 1999 Published by Elsevier Science B.V. All rights reserved.