Structural, ellipsometry and photoluminescence spectroscopy studies of silicon nanograins embedded in a silica matrix

In this paper, we deal with an ellipsometric and infrared absorption spectr oscopy (ES) studies of photoluminescent systems consisting in silicon nanog rains grown within a silica matrix by thermal annealing after magnetron cos puttering of both silica and silicon chips. The modelling of the ES spectra used a novel approach based on the effective medium approximation, which a llows us to estimate the values of excess silicon. These values were associ ated with the evolutions of both absorption coefficient and refractive inde x. The dielectric function of the inclusions was also determined and appear ed to be dependent on their nanoscaled size. This aspect enabled us to clos ely correlate the deduced dielectric function to the visible photoluminesce nce (PL) of our Si/SiO2 systems, Both energy and efficiency of the PL were found to be closely governed by the rate of silicon incorporated within the silica matrix. Finally, the infrared spectroscopy investigations gave a cl ear account of the quality of the interface between the silicon nanoinclusi ons and the silica matrix, and hence its involvement in the PL features, (C ) 2001 Elsevier Science Ltd. All rights reserved.