Structural and optical characterization of aluminum zinc co-doped tin oxide grown by sol-gel spin coating techniques

Abstract

Aluminum Zinc co-doped Tin Oxide (AZSO) thin film was grown by sol-gel spin coating techniques onto a glass substrate using various doping concentrations (0, 2, 4, 6, and 8 wt%) and the effect of doping on each sample were studied using structural analysis; X-ray Diffraction (XRD) pattern, gravimetric method; thin film thickness and UV photo-spectrometer; optical properties. The results of the XRD were revealed that all the peaks have a tetragonal phase of SnO2, which were oriented at the 110, 101, and 211 planes. The film thickness was observed to vary with doping concentration. In the visible region, all the film samples were exhibited at average transmittance. The coefficient of absorption was gradually increased with an increase in photon energy at a certain level with a decrease in the absorption coefficient as the photon energy increases further. At 550-800 nm range of wavelength, a high extinction coefficient (k) was recorded and the refractive index curves show regular dispersion behavior. The optical conductivity of the films followed a similar pattern, which showed that conductivity increased to a peak at 3.60 eV. The energy bandgap of the film samples (AZSO1 - AZSO5) is 4.095 eV, 4.103 eV, 4.087 eV, 4.114 eV, and 4.106 eV, respectively. The studies show that the properties of Al-Zn co-doped SnO2 films can be explored for optoelectronic applications.