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1 December 1991 Optical properties of amorphous hydrogenated carbon layers
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The optical properties of hard amorphous carbon layers deposited by different techniques (ECR-microwave plasma deposition, dc-plasma deposition, rf-sputtering, and electron beam evaporation) have been investigated from the middle IR up to the visible spectral regions. Refractive indices and absorption coefficient behavior have been determined by means of spectral transmittance and reflectance measurements. ECR microwave and dc-plasma deposited layers show a transparency wind w in the middle IR in the wavenumber range 1700 cm-1 < ν < 2800 cm-1. The refractive indices in the window region are between 1.9 and 2.3 with weak dispersion and show the usual increase of film mass density. However, absorption losses in the window-region are considerably higher than those in the case of diamond. For dc-plasma deposited layers, IR-absorption losses have been discussed in terms of a dispersion model, considering the absorption losses detected to be caused by a superposition of Lorentz lines and an Urbach tail. RF sputtered layers represent some kind of intermediate between graphiticlike layers (deposited by electron beam evaporation) and IR-transparent carbon formations. For rf-sputtered layers, IR-refractive indices show an extraordinary dependence on film mass density, which could be explained in terms of a mixing model, considering these layers to be built from graphiticlike and polymericlike compounds.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Olaf Stenzel, Guenther Schaarschmidt, Sylvia Roth, Guenther Schmidt, and Wolfram Scharff "Optical properties of amorphous hydrogenated carbon layers", Proc. SPIE 1534, Diamond Optics IV, (1 December 1991);

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