"Nanostructured surfaces"

Surface modification of thin nanoporous graphitic films by RF plasma treatment
Slobodyan O.M.1, Okholin P.N.1, Rusavsky A.V.1, Lytvyn P.M.1, Korchovyy A.A.1, Kondratenko S.V.2, Khyzhun O.Yu.3, Gudymenko O.I.1, Kladko V.P.1, Nazarova T.M.4, Vasin A.V.1,4, Nazarov A.N.1,4 
1 Lashkaryov Institute of Semiconductor Physics of the NAS of Ukraine, Prospect Nauki, 41, Kyiv-03028, Ukraine. 
E-mail of correspondent author: nazarov@lab15.kiev.ua
2 Faculty of Physics, Taras Shevshenko National University of Kyiv, Volodymirska str., 60, Kyiv-01033, Ukraine
3 Frantsevych Institute for Problems of Materials Science NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv - 03142, Ukraine
4 National Technical University of Ukraine “Igor Sikorsky KPI”, prospekt Peremogy, 37, Kyiv-03056, Ukraine
In this work we study RF plasma modification of the nanoporous graphitic films for enhancement of their hydrophobic/hydrophilic and sensory properties. The films were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) technique and by atomic force microscopy (AFM). Wetting of the films surface was studied by the water contact angle (WCA) technique; a resistivity of the films - by four point probes method. The samples were subjected by RF plasma treatment in hydrogen, nitrogen or argon atmosphere. 
It was shown by XRD measurements that thickness and density of the carbon film after plasma treatments are changed insignificantly and equal to about 145 nm and 1,55 g/cm3, respectively. XPS research demonstrates incorporation of nitrogen and oxygen bonds both after hydrogen and nitrogen plasma treatment and increase concentration of sp3 carbon bonds; after Ar plasma treatment introduction of nitrogen and oxygen was minor. Nitrogen and hydrogen plasma treatment resulted in decreasing of WCA up to 28° that attests increasing of their hydrophilicity whereas an argon plasma treatment increases of WCA up to 64°, that can be associated with specific surface morphology in last case which we observe by AFM. Resistivity of the hydrogen plasma treated film considerable decreases in compare with initial one while it noticeably increases after nitrogen plasma modification. Nature of the observed phenomena is analyzed and sensory properties to water vapor, ethanol and ammonia are estimated.