Dielectric and photoluminescence properties of silicon nanoparticles embedded in a silica matrix

We report an ellipsometric spectroscopy (ES) study of photoluminescent syst ems consisting of silicon nanograins grown within a silica matrix by therma l annealing after magnetron cosputtering of both silica and silicon chips. A novel approach was used for the modelling of the ES spectra which allowed us to estimate the values of excess silicon and to associate these values with the evolutions of both absorption coefficient and refractive index. Th e dielectric function of the inclusions was also deduced and correlated to the visible photoluminescence (PL) properties. The energy and efficiency of the PL was found to be closely governed by the rate of silicon incorporate d within the silica matrix. (C) 2000 Elsevier Science Ltd. All rights reser ved.