Structures and photocatalytic behavior of tantalum-oxynitride thin films

• Published in: Thin solid films Vol. 519; no. 15; pp. 4699 - 4704
• Main Authors: Hsieh, J.H., Li, Chuan, Liang, H.C.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 31.05.2011; Elsevier
• Subjects: Absorbance; Annealing; Band gap; Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Diffraction; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; General and physical chemistry; General, apparatus; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Oxynitrides; Photocatalysis; Physical radiation effects, radiation damage; Physics; Reduction; Reflectance; Sputtering; Structure of solids and liquids; crystallography; Surface and interface electron states; Surface physical chemistry; Tantalum oxynitride; Thin films; Tantalum oxynitride; Band gap; Photocatalysis; Sputtering; XRD; Deposition process; Thin films; Rapid thermal annealing; Energy gap; Reflection spectrum; Near infrared spectrum; Oxidation; Absorption spectra; Optical films; Optical absorption; Photochemical degradation; Oxynitrides; Radiation effects; Electronic properties; Visible spectra; Infrared spectra; Transmittance; Methylene blue; Reflectivity; Absorbance; Tantalum; Nitridation; Light absorption
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.01.018

Tantalum oxynitride films were created by direct nitridation/oxidation during rapid thermal annealing at temperatures 450–700 °C. Instead of during deposition, this post process may be proved to be an alternative way to make transition metallic oxynitride films. With sufficient supply of oxygen flow (≥ 30 sccm), TaO xN y was formed as examined from X-ray diffraction (XRD) analysis. This oxynitride film has a broad optical absorption over the range of visible light and sufficient photocatalytic function. For optical absorption, the films' transmittance and reflectance were measured by a UV–VIS–NIR spectrophotometer with wavelengths ranging from 300 to 900 nm. The broad visible light absorption is associated with the formation of band gap in TaO xN y film, which was examined by the theoretical calculations combining the Beer–Lambert law and Tauc formula. Lastly, the photocatalysis of TaO xN y was gauged by the photodegradation test which measured the reduction of light absorbance affected by the decomposition of methylene blue (C 16H 18N 3SCl.3H 2O) on TaO xN y under visible light irradiation.