Transmission electron microscope (TEM) techniques are useful for studying the microstructure and chemical composition on nanometer sized areas. Microdiffraction, high resolution TEM imaging and electron energy loss spectroscopy (EELS) are used to investigate the nucleation and growth of diamond films from fullerene precursors. Fine grained diamond films have been deposited on scratched silicon substrates using a microwave plasma consisitng of argon, 1- 10% hydrogen and a fullerene (C₆₀) carbon precursor. These films are exceptionally smooth as measured with an atomic force microscope, with an average surface roughness of 40-100 nm. The growth rate is comparable to that of conventional, hydrogen/methane (CH₄) microwave plasma CVD growth method, which typically results in films with >> 1 micrometers surface roughness. Grain sizes were measured from plain view bright field images from both thin and thick regions of the sample of a film grown from C₆₀ precursors. The smallest and largest grains were 3 nm and 103 nm, respectively; and the median grain size was 13 nm. Cross section TEM images reveal equiaxed diamond grains and continuous nucleation of new diamond grains throughout the growth of the film. Figures show a cross section view, high resolution TEM lattice image of a film grown from C₆₀ precursors. The silicon surface is noticeably rough from the scratching pretreatment. Microdiffraction shows the layer visible between the silicon substrate and the diamond film to be amorphous. The EELS spectrum from this 16 nm thick layer corresponds to amorphous carbon. While EELS spectrum collected from the diamond film corresponds to that of bulk diamond. Argon plasma-assisted CVD diamond films grown from C₆₀ typically nucleate on an amorphous carbon layer on the Si substrate and on diamond residue left from scratching pretreatment. Using fullerene for the precursor, there is continuous nucleation of equiaxed diamond particles throughout the thickness of the film and no columnar grain growth is observed.

Date Published: 18 August 1995
PDF: 2 pages
Proc. SPIE 2622, Optical Engineering Midwest '95, (18 August 1995); doi: 10.1117/12.216834

Published in SPIE Proceedings Vol. 2622:
Optical Engineering Midwest '95
Rudolph P. Guzik, Editor(s)