CARBON CLUSTERS IN AMORPHOUS HYDROGENATED CARBON

Direct observation is reported of diamond cluster nucleation resulting from the thermalisation of accelerated carbon atoms (ions) during gro wth of hydrogenated amorphous carbon films by ion sputtering of graphi te. Transmission electron microscopy (TEM) (100 keV), selected area el ectron diffraction (SAED) and optical absorption (1 to 6 eV) were used to study the prepared hydrogenated amorphous carbon films. The size-d istribution function of diamond crystals derived from TEM images is co nsidered in terms of the fluctuation theory. To investigate the graphi te-like constituent of a-C:H films, the optical data are analyzed unde r the assumption that the fundamental absorption edge is due to nanome ter building blocks constructed of a set of sp(2)-bonded carbon atoms assembled together as six-membered units embedded in an amorphous matr ix. A mechanism of diamond crystal nucleation is considered. (C) 1998 Elsevier Science B.V. All rights reserved.