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Proceedings Paper

Ellipsometric study of CVD diamond films prepared with various grain sizes
Author(s): Yanyan Lou; Linjun Wang; Hongliang Ma; Hongmei Deng; Bo Lu; Yiben Xia
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Paper Abstract

Diamond films with various grain sizes are grown on silicon substrates by hot-filament chemical vapor deposition method. Scanning electron microscopy (SEM) measurement shows that the films consist of diamond grain with an average crystallite size of 1.4-0.1μm. The optical and structural properties of diamond films are investigated by spectroscopic phase modulated ellipsometer in the energy range of 0.8-1.5eV. A three-layer model, Si/diamond film/diamond film + void/, is applied to diamond film based on Bruggeman effective-medium approximation and New Amorphous dispersion formula which is a rewrite of Forouhi-Bloomer formulation. By fitting spectroscopic characteristics (Ψ,Δ) with Levenberg-Marquardt regression algorithm, the energy band gap and refractive index are obtained, along with the film thickness, bulk void fraction and roughness layer. The study indicates that both energy band gap and refractive index decrease when grain size reduces due to the raise of disorder sp2 bonded carbon. The result on the Raman scattering measurement is consistent with the fitting result of spectroscopic ellipsometer.

Paper Details

Date Published: 11 March 2008
PDF: 4 pages
Proc. SPIE 6984, Sixth International Conference on Thin Film Physics and Applications, 698419 (11 March 2008); doi: 10.1117/12.792395
Show Author Affiliations
Yanyan Lou, Shanghai Univ. (China)
Linjun Wang, Shanghai Univ. (China)
Hongliang Ma, Shanghai Univ. (China)
Hongmei Deng, Shanghai Univ. (China)
Bo Lu, Shanghai Univ. (China)
Yiben Xia, Shanghai Univ. (China)

Published in SPIE Proceedings Vol. 6984:
Sixth International Conference on Thin Film Physics and Applications

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