Investigation of the structural properties of thin amorphous carbon films and bilayer structures

Thin amorphous carbon films and bilayer structures with different carbon la yers were investigated by means of both ex-situ and in-situ X-ray reflectiv ity, X-ray photoelectron spectroscopy and optical absorption spectroscopy. The films were grown either by magnetron sputtering of a graphite target or , starting from the gas phase, by ion-beam deposition and by plasma assiste d chemical vapour deposition. The X-ray reflectivity measurements revealed the existence of a transitional layer between the substrate and the film, a nd of an ultrathin transitional layer at the interface between two carbon l ayers. The structural parameters of both the films and these interfaces wer e investigated. It was found that films obtained by magnetron sputtering an d by deposition from the gas phase, in spite of having different optical an d electrical properties, have practically the same electron density. Such m ultilayer structures of constant electron density open the way to the forma tion of what could be defined 'latent superlattices'. (C) 2001 Elsevier Sci ence B.V. All rights reserved.