Optical properties of Si nanocrystals embedded in SiO2 -: art. no. 155319

The dielectric function of Si nanocrystals embedded in a SiO2 matrix has been determined in the 1.6-6.2 eV spectral range without any assumption on the dispersion law. The Si nanocrystals have been obtained by thermal annealing of SiOx layers yielding nanocrystals diameters of 4.5 nm and 1 nm for atomic composition values x of 1.1 and 1.9, respectively. The dielectric function of the large Si clusters exhibited three structures located at 3.5 eV, 4.2 eV, and 5.4 eV ascribed to the E-1, E-2, and E-1(') critical points, respectively. For the smaller Si clusters, the structure associated with the E-1 CP, near 3.5 eV, disappeared while those at higher energy remained present.