Diamond films, in micro and nanocrystalline (MCD ad/or NCD) domain, were grown on silicon substrate from graphite etching as a carbon source with atomic hydrogen, instead of using conventional hydrocarbon in the feed gas. A Graphite plate was used as sample support in a hot filament chemical vapour deposition. Scanning electron microscopy (SEM) images were used to analyze the nucleation rate of diamond films. The films grown during 15 min at 600 and 700 oC presented the higher nucleation rate with grain size in a submicrometer dimension. The high density of NCD formation in the first stage of film growth is attributed to the high amount of available carbon, even from this process governed by the graphite hydrogen etching. Micro-Raman spectroscopy demonstrated the feature of NCD coating, particularly the peak at 1150 cm-1 is attributed to trans-polyacetilene (t-Pa). Also, this high amount of NCD population in such diamond films induces a broadening and shape changes in Raman peak at 1332 cm-1. This behaviour was studied from phonon confinement model and the NCD crystallite size was evaluated in the range of 18.5 up to 14.3 nm as the in-plane correlation length La
Biografia do Autor
Sandra Cristina Ramos, Instituto Nacional de Pesquisas Espaciais
