Enhancement of the structural, optical, and optoelectrical properties of nebulizer spray pyrolyzed SnO2 thin films by strontium doping

Abstract

This work presents the fabrication of SnO₂ and Sr-doped SnO₂ thin films by spray pyrolysis at various Sr ratios. The influence of Sr doping on the structure, optical, and optoelectrical characterizations has been investigated. The XRD investigations confirmed that the Sr-doped SnO₂ layers exposed orthorhombic structures. The structural results illustrate that the growth in Sr content to 2.5 % w.t enhances the crystallite size and reduces the values of ${\epsilon }_s$, N_C, and $\delta$ of the pure and Sr: SnO₂ layers. Furthermore, the boost of the Sr content to 5 % w.t and 7.5 % w.t enhances the values of ε_s, N_C, and δ of the pure and Sr: SnO₂ layers and reduces the crystallite size. The optical analysis of these layers displays an enhancement in the refractive index values from 2.37 to 4.81, Urbach energy from 0.138 to 0.176 eV, and dispersion energy values from 12.48 to 15.66 eV by enlarging the Sr concentration. The energy gap results of the inspected films showed that boosting the Sr concentration reduces the E_g values from 3.78 to 3.04 eV. Furthermore, the optoelectrical parameters of the Sr-doped SnO₂ samples, like the optical mobility, plasms frequency, optical dielectric indices, optical carrier concentration, and optical resistivity, were boosted by enlarging the Sr concentration. Furthermore, increasing the Sr content in these films increases the nonlinear refractive index and the nonlinear susceptibility of the pure and Sr: SnO₂ layers.