Light scattering in nanocrystalline silicon-carbide (nc-SiC) films

Abstract

Correlations between the optical and structural characteristics of nanocrystalline silicon-carbide (nc-SiC) films prepared by direct ion deposition onto sapphire substrates are studied. The effect of the scattering of electromagnetic radiation in nc-SiC films on their optical characteristics (transmittance, reflectance, and absorbance) is investigated. It is shown that in nc-SiC films deposited at temperatures <700°C scattering is minimum due to their morphological and structural homogeneity. The films deposited at >1000°C exhibit significant morphological and structural heterogeneity and therefore strongly scatter light. It is established that the account for light scattering leads to a blue shift of the fundamental absorption edge in the optical density spectra. The spectra of the scattering coefficients for the nc-SiC films are studied and calculated. The effect of high-temperature annealing on the film structure and scattering spectra is investigated. It is demonstrated that the structural variations induced by annealing are accompanied by a change of the initial mechanism of Rayleigh scattering in the nc-SiC films for the Mie scattering.