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This paper reports the deposition and characterization of nanocrystalline carbon thin films by filtered cathodic jet carbon arc technique assisted with three different gaseous environments of helium, nitrogen and hydrogen. All the films are nanocrystalline in nature as observed from the high resolution transmission electron microscopic (HRTEM) measurements, which suggests that the nanocrystallites of size ∼10–50 nm are embedded though out the amorphous matrix. X-ray photoelectron spectroscopic studies suggest that the film deposited under the nitrogen gaseous environment has the highest sp 3 /sp 2 ratio accompanied with the highest hardness of ∼18.34 GPa observed from the nanoindentation technique. The film deposited under the helium gaseous environment has the highest ratio of the area under the Raman D peak to G peak ( A D / A G ) and the highest conductivity (∼2.23 S/cm) at room temperature, whereas, the film deposited under the hydrogen environment has the lowest conductivity value (2.27 × 10 −7 S/cm). The temperature dependent dc conduction behavior of all the nanocrystalline carbon thin films has been analyzed in the light of Mott’s variable range hopping (VRH) conduction mechanism and observed that all the films obey three dimension VRH conduction mechanism for the charge transport. [ABSTRACT FROM AUTHOR]

Abstract: The effect of substrate bias on the structural, morphological, electrical and mechanical properties of hydrogenated amorphous carbon films having embedded nanocrystallites deposited by cathodic jet carbon arc technique has been investigated. X-ray diffraction exhibits predominantly an amorphous nature of the film with nanocrystallites of diamond embedded in the amorphous carbon matrix. High resolution transmission electron microscope investigations reveal largely a uniform amorphous structure. However, an ultra fine microstructure with the average grain size between 8 and 25nm was constituting the entire film with the diffused grain boundaries between the grains. Majority of the individual grains are single crystallite with the preferred inter planar spacing of about 0.213nm and 0.208nm corresponding to the diamond planes of 102 and 103, respectively. All the evaluated parameters were seen to depend strongly on the negative substrate bias and exhibit maxima or minima in the properties of the films deposited at −60V substrate bias. [Copyright &y& Elsevier]