Thin a-C:H:Si:O:N films were deposited from plasmas fed hexamethyldisiloxane, oxygen and nitrogen, and characterized as a function of the partial pressure of oxygen in the feed, R ox . Deposition rates varied from 10 to 27 nm min -1 . Surface roughness was independent of R ox , being around 10 nm. The films contain C=C and C=O, and also Si-C and Si-O-Si groups. Lower [C] and [N] but greater [O] and [Si] were measured in the films as R ox was increased. Refractive indices of ~ 1.5 and optical energy gaps which fell from ~ 3.3 to ~2.3 eV were observed with increasing R ox . The Urbach energy fell with increasing optical gap, which is characteristic of amorphous materials. Such materials have potential as transparent barrier coatings.
Thin a-C:H:Si:F:N films were studied as a function of the partial pressure of SF 6 in plasma feed, R SF , together with tetramethylsilane and N 2 . Deposition rates varied from ~4 to ~19 nm.min -1 . Surface roughnesses were typically less than 35 nm. Surface contact angles with water droplets, measured using goniometry, were all around 90°. Scanning electron micrography revealed surface particles, probably formed in the gas phase, of typical diameters ~8 μm. As revealed by Fourier transform infrared spectroscopy and energy dispersive x-ray spectroscopy, the films are plasma polymers with a carbon and silicon network. Most of the films contain ~ 60 at.% C, ~ 10 at.% Si, 20 at.% O and ~5 to 14 at.% N. Film doping with F rises to ~2 at.% as R SF is increased. The Tauc gap, calculated from ultraviolet-visible near infrared spectroscopic data, is controllable in the range of ~3.5 to 4.1 eV by a suitable choice of R SF . Fluorination causes the films to be softer and less stiff. Total deformation and stored energies are reduced compared to those of the film deposited at R SF = 0%. The modulus of dissipation increases from ~8% to a maximum of ~65% for the fluorinated films.
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