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Proceedings Paper

Tailored TCOs
Author(s): Astrid Bingel; Kevin Füchsel; Norbert Kaiser; Andreas Tünnermann
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Paper Abstract

The metal-like electrical conductivity in combination with a high visual transmittance is the characteristic property that opens up a broad spectrum of applications to transparent conductive oxides (TCOs). To fulfill the manifold requirements in each individual case, especially the optical properties of TCOs have to be adapted. The transmittance in the near infrared spectral range can be tailored by a modification of the carrier concentration Ν and mobility μ. The theoretical description for this behavior is based on the well-known Drude theory. Highly conductive indium tin oxide films (ITO) have been prepared by pulsed DC magnetron sputtering. However, due to its excellent electrical properties, the plasma resonance of free carriers occurs near the visual spectral range which results in a very low transmittance in the NIR. In contrast, ITO films with a NIR transmittance of ca. 80% have been prepared by plasma ion assisted evaporation. The combination of high transmittance and low resistivity of ρ=7.4x10-6Ω was achieved by a decrease of the carrier concentration and a simultaneous enhancement of the electron mobility μ. Secondary, the transmittance of aluminum doped zinc oxide films (AZO) in the UV spectral range could be adapted by changing the doping concentration Ν. This is a direct consequence of the Burstein-Moss shift that leads to a band gap widening dependent on Ν. However, the comparison of the experimental data with theory has shown that the contrary effect of band gap narrowing is not negligible, too.

Paper Details

Date Published: 3 October 2011
PDF: 9 pages
Proc. SPIE 8168, Advances in Optical Thin Films IV, 81680R (3 October 2011); doi: 10.1117/12.896774
Show Author Affiliations
Astrid Bingel, Friedrich-Schiller-Univ. Jena (Germany)
Kevin Füchsel, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Norbert Kaiser, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)

Published in SPIE Proceedings Vol. 8168:
Advances in Optical Thin Films IV
Michel Lequime; H. Angus Macleod; Detlev Ristau, Editor(s)

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