Study of thin amorphous and crystalline carbon films by electron microscopy

Dark-field pictures of a thin carbon film deposited at room temperature and of a film annealed at 1050°C have been compared and suggest totally different structures for these two carbons. Pictures of the film deposited at room temperature correspond to what is expected from a tetrahedral random network model. Pictures of the annealed films correspond to turbostratic stacks of aromatic carbon layers. These annealed films show a preferred orientation of the layers, parallel to the film surface. This anisotropy is induced by the solid-vacuum interface of the thin carbon film, as nucleation of aromatic molecules by annealing takes place.