Plasma treatment as a versatile tool for tuning of sorption properties of thin nanoporous carbon films

Abstract The chemical and structural modification of thin nanoporous graphitized carbon film was achieved by RF plasma treatment in the atmosphere of Ar, N2 and H2 + N2. The effect of carbon surface modification on the resistive sensitivity of gas sensor to water and ammonia vapors is studied. It was shown, that nitrogen and forming gas plasma treatments result in the same surface morphology (short and long-range behavior) and chemical modifications (introduction of pyridinic and pyrrolic nitrogen bonds), without noticeable changes of the film thickness and porosity. Such plasma treatments lead to surface hydrophilicity (on macro- and micro-levels) with increased surface energy and reduction of sensitivity to water vapor (from 22% to 3%), while adsorption rate and sensitivity to ammonia vapor increase. Argon treated film was found to have lower surface roughness, concentrations of oxygen and nitrogen bonds, which results in strong increasing of hydrophobicity and decreasing of water vapor sensitivity (to 8%).