Regensburg 2004 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 22: Postersitzung

DS 22.43: Poster

Dienstag, 9. März 2004, 14:30–17:00, Poster B

Multitechnique characterization of tantalum oxynitride films prepared by reactive DC magnetron sputtering. — •Selvaraj Venkataraj, Achim Breitling, and Matthias Wuttig — I. Physikalisches Institut (1A) der RWTH Aachen, 52056-Aachen

Reactive DC magnetron sputtering is an important technique to deposit optical coatings, which frequently employ transition metal oxides. Since sputtering of such oxides often is accomplished by process instabilities (arcing) and low deposition rates, we have deposited oxynitride films by sputtering in a mixed gas atmosphere. The total pressure was kept constant at 0.8 Pa, and both oxygen and nitrogen partial pressures have been adjusted to maintain a constant total pressure. The corresponding films have been characterized by a variety of techniques including X-ray diffraction, X-ray reflectometry, optical spectroscopy, spectroscopic ellipsometry and Rutherford backscattering. Addition of nitrogen leads to a beneficial increase of film properties. The sputter rate increases from 0.27 to 0.46 nm/s and also the film density increases from 7.15 to 8.65 g/cm³. This leads to an increase of refractive index of the films. Even for films with a high refractive index around 2.5, the band gap is found to be above 2.5 eV, i.e., fully transparent films are obtained. The correlation of deposition parameters and the resulting film properties will be discussed.

Acknowledgement: One of the authors (S.Venkataraj) would like to thank Alexander von Humboldt-Stiftung for a fellowship to carry out this work at I. Physikalisches Institut (IA) der RWTH-Aachen.