Boron-doped TiO2 (B-TiO2) Thin Films Grown Using Sol-Gel Spin Coating Method

Abstract

In this study, the effect of modifying boron doping concentration on the optical properties, electrical properties and microstructural images of TiO2 thin films was investigated by the sol-gel technique by grinding TiO2 powder with a boron compound at a wavelength range of 250 nm to 850 nm. The SEM micro-images revealed the homogenous, continuous and nanocrystalline surface morphology: 10% is the tolerable amount of boron doping concentration into the TiO2 for achieving sphere-like nanostructures materials with low agglomeration. The XRD spectra of the B-TiO2 films showed anatase peaks of greater intensities when compared to the pure TiO2 film. All the films illustrate extinction coefficient in the visible region of solar spectra corresponding to the low absorption, and absorption peaks established in the ultraviolet region near 330nm with the optical transmittance varied from over 52 - 96% in the UV-Vis wavelength range. Diffuse reflectance absorption spectra analysis indicated that the incorporation of B into TiO2 material results in a substantial red shift and the absorption extends significantly into the visible range. The optical band gap energy values of the thin films were found to be 3.38, 3.35, 3.28, 3.26, and 3.36eV. This showed a low probability of raising the electron across the mobility gap with the photon energy in the visible region. The refractive index values varied between 1.891 and 1.922 depending on the percentage content of boron. Moreover, the imaginary part of the dielectric constant increase slowly, whereas the real part increases sharply and the optical conductivity was found to increase with the increase in boron addition.