Electronic and optical properties of granular amorphous carbon films

Amorphous carbon (a-C〈N〉) films on glass substrates are obtained by magnetron sputtering of a graphite target in nitrogen. The temperature dependence of the electric conductivity (lnσ≈T ^1/2 at temperatures T<280 K) of the films is typical of a granular structure. The results of measurements of the thermo emf, conductivity, and optical absorption of the a-C〈N〉 films suggest that the granular structure comprises nanodimensional clusters of γ-carbon phase with metallic conductivity distributed in a graphitelike carbon matrix. The concentration of such clusters in the matrix increases with the substrate temperature.