Precursor concentration effect on the physical properties of transparent titania (Anatase-TiO2) thin films grown by ultrasonic spray process for optoelectronics application

Abstract

Titanium oxide TiO2 thin films have been deposited on heated glass substrates at 0.02, 0.05, 0.1and 0.2 M of precursor concentration by ultrasonic spray process, using the titanium tetra iso-prop-oxide (TTIP) as Ti source. The present study focuses on the physical properties of TiO2 thin film as a function of precursor concentration. Furthermore, deposited thin films were systematically investigated using X-ray diffraction (XRD), scanning electron microscope, energy-dispersive X-ray (EDX) spectra, Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometer and four-point probe measurement. The X-ray diffraction analysis shows that TiO2 films have the tetragonal structure of anatase with a preferential growth along the (101) direction. The crystallite size of TiO2 films increases from 30 to 47 nm with increasing precursor concentration. The SEM images reveal uniform, homogenous and dense film with good adhesion to the substrate surface. In addition, EDX analysis confirms the presence of all elements forming TiO2 material. The films optical transmittance attains 86% in the visible region, while the optical band gap of the films decreases from 3.47 to 3.32 eV (the red-shifted absorption edge). Finally, the electric resistivity of the prepared films decreases from 158 to 56 Ω cm with increasing the precursor concentration.