Characteristics of hydrogenated amorphous carbon films deposited by large-area microwave-sustained surface wave plasma

In this study, we report the characteristics of hydrogenated amorphous carbon (a-C:H) films grown at room temperature by chemical vapor deposition (CVD) with a 40-cm diameter planar surface wave plasma in a He/CH4 gas mixture. The film characteristics such as electron field emission and the atomic or molecular bonding structures, measured with XPS, FT-IR spectrophotometry and NMR analysis, have been studied. The electron emission current density of 1 muA/cm(2) was obtained at an electric field of 4 V/mum in the 'as-grown' a-C:H film. From the NMR measurements, it is found that the a-C:H film typically contains 25% of graphite-like sp(2)-carbon bondings and 75% of sp(3)-carbon bondings with one or more hydrogen atoms. The results of electrical conductivity measurements of a-C:H films suggest that spatially localized conduction channels formed by the Praphite-like sp(2)-carbons might be responsible for the electron emission in the a-C:H films by locally-enhanced electric fields. (C) 2002 Elsevier Science B.V. All rights reserved.