Pyrocarbon Deposits on a Graphite Surface Observed by STM (original) (raw)

Chemical Vapor Deposition, 2001

Abstract

The CVD of carbon materials is a complex process leading to different types of pyrocarbons, in particular rough laminar (RL) and smooth laminar (SL) microstructures. In the current study, we examined the behavior of the gas-solid interface during the nucleation and growth processes of pyrocarbons. Using a classical, isothermal-isobaric CVD technique, we prepared deposits on ideal pyrographite surfaces. In order to investigate the first deposition steps, we studied short deposition times for various residence times giving rise to either RL or SL pyrocarbons. Using scanning tunneling microscopy (STM) on different scales, we observed these deposits and measured the associated contact angles. The two typical microstructures, SL and RL, were found to be related to different types of heterogeneous nucleation. The controlled morphological change can be interpreted as a sort of wetting transition of the pyrographite surface, associated with the surface chemical reactions. Indeed we have clarified the role of interfacial interactions in the origin of these different classes of pyrocarbon deposits.

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