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Optical properties and surface morphology of evaporated (WO 3)1-x-(Fe2O3)x thin films

Moshfegh, A. Z ; Sharif University of Technology | 2005

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  1. Type of Document: Article
  2. DOI: 10.1016/j.tsf.2005.02.019
  3. Publisher: 2005
  4. Abstract:
  5. Thin films of (WO3)1 - x-(Fe2O 3)x composition were deposited by thermal evaporation on glass substrates and then all samples were annealed at 400 °C in air. Optical properties such as transmittance, reflectance, and optical bandgap energy of the "as deposited" and the annealed films were studied using ultraviolet-visible spectrophotometry. It was shown that the annealing process did not substantially change the optical transmittance and reflectance of all the films except the films having x = 0.75. By increasing Fe2O 3 content in the films from x = 0 to x = 0.75, optical bandgap energy decreased from 3.4 to about 1.3 eV and from 3.1 to 2.1 eV for the "as deposited" and the annealed samples, respectively. Moreover, using X-ray photoelectron spectroscopy, we have shown that the "as deposited" (WO3)0.25-(Fe2O3)0.75 films contained Fe3O4, and it converted to Fe 2O3 after the annealing process. Using atomic force microscopy, it was found that the grain size and surface roughness of the annealed films were greater than the "as deposited" ones. In addition, for the annealed films with intermediate x's, we have observed a smoother surface with smaller grain size as compared to films with the other x's. © 2005 Elsevier B.V. All rights reserved
  6. Keywords:
  7. Atomic force microscopy ; Energy gap ; Evaporation ; Grain size and shape ; Iron oxides ; Light reflection ; Light transmission ; Morphology ; Refractive index ; Spectrophotometry ; Surface roughness ; Tungsten compounds ; X ray photoelectron spectroscopy ; Amorphous structures ; Optical bandgap energy ; Thermal evaporation ; Valence states ; Thin films
  8. Source: Thin Solid Films ; Volume 484, Issue 1-2 , 2005 , Pages 124-131 ; 00406090 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0040609005002026