Spectroscopic Ellipsometric Study Of Size-Controlled Silicon Nano-Crystals In Sio2 Composite Thin Film

In this work, a series Of SiOx/SiO2 superlattices were prepared, by using reactive evaporation, with different thicknesses of the SiOx layers. After being annealed at 1100 degrees C, composite thin films with the nano-crystals of silicon (nc-Si) embedded in the SiO2 layers were formed. The optical properties of the films were measured by using the spectroscopic ellipsometric (SE) method in the photon energy range from 1.5 to 4.5 eV at three different incidence angles of 65 degrees, 70 degrees and 75 degrees. In terms of the ellipsometric data, the effective medium approximation (EMA) with the four-parameter Lorentz oscillator model was used to fit the spectra and to extract the optical dispersion of the nc-Si particles. We found that the dielectric functions of the composite films strongly depended on the volume fraction of nc-Si and the constant of the SiO2 layers, which changed with the composition in the investigated spectrum range.