Structural and optical properties of zinc oxide thin films prepared by spray pyrolysis method


Gumus C., Ozkendir O., Kavak H., Ufuktepe Y.

JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, vol.8, no.1, pp.299-303, 2006 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 8 Issue: 1
  • Publication Date: 2006
  • Journal Name: JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.299-303
  • Keywords: ZnO, optical properties, thin films, spray pyrolysis, EXAFS, TRANSPARENT CONDUCTING ZNO, SOLAR-CELLS, DEPOSITION, GROWTH, AL
  • Çukurova University Affiliated: Yes

Abstract

Polycrystalline ZnO thin films were deposited on a glass substrate by a spray pyrolysis technique using solution of zinc acetate and air as the carrier gas at 400 degrees C temperature. Optical constants such as refractive index n and extinction coefficient k, were determined from transmittance spectrum in the ultraviolet-visible-near infrared (UV-VIS-NIR) regions using envelope methods. The films were found to exhibit high transmittance (> 90 %), low absorbance and low reflectance in the visible regions. Absorption coefficient a, and the thickness of the film t were calculated from interference of transmittance spectra. The energy band gap, and the thickness of the films were evaluated as 3.27 eV and 0.31-0.52 Pm respectively. The crystallographic structure of these films was analyzed with x-ray diffractometer. The films were polycrystalline in nature with preferred (002) orientation perpendicular to substrate surface and the grain size estimated to be 40 nm. The extended x-ray absorption fine structure (EXAFS) calculations above the K-edge of Zn in the ZnO thin film have been performed by using real-space multiple scattering of photoelectrons. For ZnO thin films, the values of the correlated mean square relative displacements of nearest-neighbor atoms derived from EXAFS spectra show good agreement with those measured from the x-ray diffraction experiments.