Effect of UV irradiation on the linear and nonlinear optical properties of Erbium(III)-Tris(8-hydroxyquinolinato) thin films: optoelectronic performance

Abstract

Thin films of Erbium(III)-Tris(8-hydroxyquinolinato) (Erq3) were prepared by the thermal evaporating technique. The structural properties of the UV-irradiated films were investigated by XRD-pattern. The analysis of the XRD-Pattern revealed the polycrystalline structure for the as-deposited Erq3 film, whereas the amorphous structure was observed for the UV-irradiated films. Hence, the optical properties were significantly affected by the sublevels of energy produced by the induced defects. For instance, the band gap energy was lowered by an amount of 16.6% from its original value when the films were exposed to UV-irradiation for 120 min. Whilst, the normal dispersion values increased by an amount of 18.2% when the films were exposed to UV radiation for 120 min. According to the single oscillator, the dispersion parameters ( and ε ∞ ) were evaluated. The nonlinear optical parameters such as third-nonlinear optical susceptibility and the nonlinear refractive index were discussed under the effect of UV radiation. It was noticed the impact of UV-irradiation in increasing the value, and therefore the UV-irradiation Erq3 films possess the probability to be used in the nonlinear optical materials. The effect of UV-radiation on the dielectric constants of Erq3 films was also explained.