Nitrogen-induced nanostructure formation in hydrogenated amorphous carbon films doped with nitrogen

Hydrogenated amorphous carbon films were deposited with (a-C:H–N) and without (a-C:H) nitrogen incorporation on p-type silicon, quartz and indium-tin-oxide (ITO)-coated glass substrates by microwave-assisted surface-wave plasma chemical vapor deposition using C2H4 and C2H2 as a source gas, Ar as a carrier gas and N2 for incorporation. Films were studied using field emission scanning electron microscopy, energy dispersive X-ray analysis (EDAX) and ultraviolet–visible–near infrared spectroscopy. a-C:H films on silicon are observed to have very smooth morphology whereas the films become nanoparticulate one at higher nitrogen content in the film. Particulate formation is observed to be more pronounced on ITO substrate when compared with the simultaneously deposited films on silicon. Compositional study by EDAX indicates that nitrogen concentration is much larger (considering carbon concentration) in the films on ITO as compared to those on silicon. These observations clearly indicate that nitrogen induces nanoparticulate formation in a-C:H–N films by providing more curvature to carbon lattice, as nitrogen prefers non-planer configuration.