Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory

Journal Article · Wed Aug 15 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4748166· OSTI ID:22089414

Valyukh, I. ^[1]; Green, S. V.; Granqvist, C. G.; Gunnarsson, K.; Niklasson, G. A. ^[2]; Arwin, H. ^[1]

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1. Laboratory of Applied Optics, Department of Physics, Chemistry and Biology, Linkoeping University, SE-58183 Linkoeping (Sweden)
2. Department of Engineering Sciences, Angstroem Laboratory, Uppsala University, P.O. Box 534, SE-75121 Uppsala (Sweden)

Films of Ni{sub x}W{sub 1-x} oxide with 0.05 {<=} x {<=} 0.53 were produced by reactive dc magnetron co-sputtering onto Si. Such films have documented electrochromism. Spectroscopic ellipsometry was used to extract accurate data on the dielectric function in the photon range 0.062 to 5.62 eV. The results for 0.62 to 5.62 eV were compared with computations from the Bruggeman effective medium theory applied to two nanostructural models: one representing a random mixture of structural entities characterized by the dielectric functions of WO{sub 3} and NiWO{sub 4} and the other describing a random mixture of WO{sub 3} and NiO. Unambiguous evidence was found in favor of the former model, and hence the films are composed of nanosized tungsten oxide and nickel tungstate. This agrees excellently with an earlier investigation of ours on Ni{sub x}W{sub 1-x} oxide films, where nanostructure was inferred from Raman spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction.

• OSTI ID: 22089414
• Journal Information: Journal of Applied Physics, Vol. 112, Issue 4; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DEPOSITION
DIELECTRIC MATERIALS
ELECTROCHROMISM
ELLIPSOMETRY
INFRARED SPECTRA
MAGNETRONS
NANOSTRUCTURES
NICKEL ADDITIONS
NICKEL OXIDES
NICKEL TUNGSTATES
OPTICAL PROPERTIES
RAMAN SPECTRA
RAMAN SPECTROSCOPY
RANDOMNESS
THIN FILMS
TUNGSTEN OXIDES
ULTRAVIOLET SPECTRA
VISIBLE SPECTRA
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY