## 3 Results and Evaluations
### Properties of Ag+ SiC Nanocomposite Layers on Optical Glass Substrates  
Figure 4 shows the optical characterization results obtained. It can be seen that the measured transmission spectrum was fitted with the modeled transmission spectrum, to re-confirm the actual layer thickness. It was found that the transmission spectrum of the as-deposited composite films matched that of a 50 nm modeled layer. However, after the heat treatment (tratled annealing runs between 200-450 \({}^{\circ}\)C for an hour), slight changes in the transmission spectra were observed (as can be seen in Figure 4a).  
A small hump on the spectral response of the as-deposited composite layer was observed in comparison to that of the modeled layer; however, significant spectral shifts were observed in all of the high-temperature (above 300 \({}^{\circ}\)C) heat-treated films. The modeling of the nanocomposite layer transmission involved using a weighted average of the dielectric  
Figure 2: Extrapolated digitized optical constants dispersion data (**a**,**b**), and the optical (**c**) [32], and color (**d**) characterization results for thin sputtered Ag layers. The color values (measured using Minolta 508D) for different Ag thicknesses show the variation in ARY versus Ag layer thickness, which reflects the importance of characterization for optimum film development.  
permittivities of the material components, using OptiLayer software. All of the heat-treated samples showed comparatively smoother transmission spectra, which might imply that the additional SiC compound transforms from the amorphous phase to the quasi-crystal stage, and this helps protect the pure-silver content from agglomeration or turning into nanoparticles. From the measured transmission spectrum of the as-deposited composite layer, we numerically evaluated the possible range of the absorption coefficient of the composite film, across a wide spectrum. Figure 4b shows the obtained wavelength-dependent absorption coefficient plotted within its possible upper and lower limits, compared to that of a pure silver layer. The upper and lower limits were evaluated by considering the maximum \(\pm\)5% thickness error.  
Figure 5 shows the morphological study results obtained on pure silver (Ag) and nanocomposite (Ag+ SiC) layers (subjected to dry heat exposure in the same conditions). It can be seen that the pure Ag layer turned into nanoparticles (the size and shape of the nanoparticle were relatively large, Figure 5a,b) while the composite layer showed resistance to turn into distinguishingly notable sizes of nanoparticles (Figure 5c,d). These results indicate that our composite material can withstand comparatively higher temperatures that are necessary for the production of high-standard commercial optical coatings. In the coating industries, the coating chamber temperature exceeds 180 \({}^{\circ}\)C where a pure metal layer can easily be turned into nanoparticles or can be oxidized due to the influence of the adjacent oxide layer of the coating structure.  
Figure 6 shows all the elemental constituents present in the Ag-based (SiC dilute) metallic composite thin films. It can be noticed that there is a large peak of Si observed which we believe is due to the presence of Si in the substrates (glass).  
Figure 3: Optical transmission spectrum of an amorphous SiC layer prepared by using RF magnetron sputtering technique.  
Figure 4: Optical characterization results were obtained from Ag+ SiC thin-film nanocomposite layers (**a**) transmission spectra and (**b**) optical absorption coefficient.