Optical properties of (TiO2)1-x(CuO)x pseudo binary oxides thin films prepared by spray pyrolysis technique

The pseudo binary oxide thin films were prepared by spray pyrolysis technique on cleaned quartz and silicon substrates at a substrate temperature of 350 degrees C. The X-ray diffraction reveals that the obtained films show anatase phase and mixed phase of copper titanium oxide (Cu3TiO4) for TiO2-CuO films. The surface morphology as observed from SEM image shows spherical grains and rough surface structure of TiO2-CuO films. The EDAX provides the chemical elemental analysis, which reveals that with increase of CuO oxygen weight percentage found to decrease. In an optical study the transmittance and reflectance spectra were recorded in normal incidence by UV-Visible spectrophotometry in the wave length range 350-1200 nm. Using these optical data estimated the thickness, refractive index, and extinction coefficient, real and imaginary parts of dielectric constants of the TiO2-CuO films. It is observed that, with the increase in molar fraction there is variation of the optical parameter, which may be attributed to the mixed phase formation in the films as well as the formation of defects. The increasing Cu contents estimated energy band gap decreases and grain size decreases which leads to decreasing surface resistivity; hence TiO2-CuO films are further used for photovoltaic cell application.