Schottky barrier formation on rf-plasma enhanced chemical vapour deposited hydrogenated amorphous carbon

This paper reports the fabrication and electrical characterization of sub-micron metal contacts to thin films of hydrogenated amorphous carbon deposited by the r.f.-plasma enhanced chemical vapour deposition technique. The I-V characteristics of "large" area (diameter 0.5 mm) top metal contacts to amorphous carbon are consistent with bulk limited conduction by the Poole-Frenkel mechanism. The I-V characteristics of sub-micron metal contacts, formed at different locations on the same amorphous carbon film, range from symmetrical to highly asymmetrical with forward-to-reverse rectification ratios up to three orders of magnitude. Asymmetrical I-V characteristics and a linear C-2-V response confirm, for the first time, Schottky barrier formation at the metal/amorphous carbon interface. Spatial non-uniformity in the composition of the hydrogenated amorphous carbon surface is indicated, which mirrors bulk inhomogeneity. (C) 1998 Published by Elsevier Science S.A. All rights reserved.