HFCVD DIAMOND NUCLEATION AND GROWTH ON DLC CARBON-FILMS OBTAINED BY LASER-ABLATION

Diamond deposition by hot filament chemical vapour deposition (HFCVD) on DLC films prepared by laser ablation (5 nm < thickness <20 nm) was studied by electron spectroscopies, including X-ray photoemission, Aug er electron and electron loss spectroscopy directly connected to the H FCVD growth chamber. It is shown that, whatever the thickness and the annealing procedure, this carbon layer is removed in the gas phase or reacts with silicon to Form a silicon carbide layer as soon as the typ ical operative conditions for diamond growth are implemented (1073 K a nd 0.5% CH4 diluted in H-2). The instability of this carbon layer is a scribed to the etching behaviour of highly reactive hydrogen radicals at the high temperature of the diamond growth (1073 K), especially wit h carbon of graphitic form. Moreover, both the thickness of the carbon films and the annealing temperature greatly influence the diamond nuc leation density. (C) 1998 Elsevier Science Ltd. All rights reserved.