Improvement of structural, optical and electrical properties of iron doped indium oxide thin films by high gamma radiations for photocatalysis applications

Iron doped indium oxide (In2O3:Fe) thin films have been deposited on glass substrates by spray pyrolysis technique and irradiated by four high gamma doses 1, 5, 10 and 100 kGy. We have investigated the influence of applied gamma radiations on structural, optical, photoluminescence and electrical properties of In2O3:Fe thin films using X-ray diffraction, Raman spectroscopy, spectrophotometer, Photoluminescence spectrometer and Hall Effect measurements. Structural analysis revealed that preferred orientation (400) plan depicted at 2θ = 35.5° was kept after exposure to gamma radiations with a noticeable improvement of crystallinity for all doses. Average transmission values in the transparent domain [600-2500] nm were increased from 79% to a maximum value of 88% for irradiated thin layer by 10 kGy. Band gap energy was also increased from 3.32 eV to 3.5 eV after irradiation by 10 kGy. Different optical parameters such as refractive index n(λ), extinction coefficient K(λ), lattice dielectric constant (εL), high frequency dielectric constant (ε∞), plasma frequency (ωP) and the ratio of carrier concentration to electron effective mass (Nm*) were determined and analyzed. Single-oscillator Wemple-Didomenico model was applied to calculate the dispersion parameters E0 and Ed after gamma irradiation. Photoluminescence spectra of thin films show an overall decrease in their peak intensities after γ-irradiation. Hall Effect measurements of In2O3:Fe thin films revealed that electrical resistivity have been decreased from 5.07 * 10−2 Ω cm to a minimum value of 1.75 * 10−2 Ω cm at 10 kGy. All these good experimental results can lead to a potential use of gamma irradiated iron doped indium oxide thin film for optoelectronic devices. Photocatalytic activity of γ-irradiated In2O3:Fe thin films to decompose methylene blue were studied under sun light. Optimum irradiated thin film shows an enhancement of photocatalytic activity under sun light with a percentage of dye decolorization equals to 87%.