Optical Study of Ultrathin TiO2 Films for Photovoltaic and Gas Sensing Applications

  • Arturas SUCHODOLSKIS Center for Physical Sciences and Technology
  • Alfonsas RĖZA Center for Physical Sciences and Technology
  • Virginijus BUKAUSKAS Center for Physical Sciences and Technology
  • Audružis MIRONAS Center for Physical Sciences and Technology
  • Arūnas ŠETKUS Center for Physical Sciences and Technology
  • Irena ŠIMKIENĖ Center for Physical Sciences and Technology
Keywords: thin films, TiO2, transition metal oxides, ellipsometry

Abstract

TiO2 ultrathin films of thickness below 20 nm were deposited by reactive RF magnetron sputtering. The optical properties of TiO2 films were investigated by various optical techniques including UV-VIS-NIR spectroscopic ellipsometry. The Scanning Probe Microscopy (SPM) was used to determine thickness and surface roughness of the deposited films. The correlation between preparation conditions of ultrathin TiO2 films and their physical properties has been studied.

The analysis of optical data revealed the parameters of deposited films and intrinsic properties of TiO2 material before and after annealing. We found that deposited layers were predominantly amorphous with high porosity at the top sample, and absence of porosity at the bottom of TiO2 layer. Annealing considerably improves structural order of the studied samples and the film transforms to the polycrystalline anatase phase. Also we evaluated the energy bandgap (about 3.1 eV3.2 eV) which increases after annealing (above 3.3 eV) and it is  close to the bandgap of anatase.

DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6328

Published
2014-06-13
Section
ELECTRONIC AND OPTICAL MATERIALS