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Color dependency on optical and electronic properties of TiN thin films

Nikolaos P. Kalfagiannis ,  Stergios Logothetidis 

Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology, Aristotle University Campus, Thessaloniki GR-54124, Greece

Abstract

In this work we present in-situ and real-time Spectroscopic Ellipsometry (SE) spectra analysis as a tool for investigation of the relation and the underline physics between visual appearance and the optical and electronic properties of TiNx nanocrystalline coatings. The films were fabricated employing Reactive Magnetron Sputtering in an unbalanced configuration. We also present a comparison between the electronic properties of these thin films and TiNx coatings fabricated with balanced magnetron sputtering, which their results have been reported in our previous work. Deposition was carried out at various values of substrate bias voltage and N2 pressure. Insights on the optical and electronic properties were arisen from the analysis os SE spectra, using the combined Drude-Lorentz model, which describes the optical response of the conduction and valence electrons. The energy, strength and the conduction electron density, were studied with respect to the bias voltage. The observed color variations can be resolved in terms of the Drude-Lorentz model. The onset of the interband transitions is responsible for the color of the nanocoatings and occurs in lower energies than the calculated transition energies. This weak absorption, which is the fundamental interband transition, cannot be experimentally identified and discriminated from the strong, dominating contribution of the intraband absorption of the SE spectra at low photon energy. For the determination of this weak interband transition we used the Tauc-Plot method. Finally, we associated this energy with the screened plasma energy, therefore with the stoichiometry, and with the grain size of the coatings as well.

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2006, Symposium A, by Nikolaos P. Kalfagiannis
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 19:46
Revised:   2009-06-07 00:44