Effect of Aluminum Doping on Structural and Nonlinear Optical Properties of Tin Dioxide Films Prepared by Spray Pyrolysis

Abstract

This study evaluated the impact of Al doping with ratios of 3%, 5%, and 7% on the structural and non-linear optical properties of SnO₂ thin films deposited using the spray pyrolysis method. X-ray diffraction revealed a polycrystalline and tetragonal structure of the films with no phase change of the SnO₂ films. The EDX/SEM pictures reveal spherical, semi-spherical, and agglomerated nanoparticles aggregated in varied patterns and densities with Al atoms entangled inside the crystalline lattice of SnO₂. The open aperture Z- scan measurements revealed an increase in the TPA coefficient (β_eff) at doping levels below 7% in comparison to higher doping concentrations. Closed aperture configuration demonstrated an enhancement in the nonlinear refractive index and in turn the susceptibility χ⁽³⁾. The enhancement in the structural and nonlinear optical properties of SnO₂ with the doping permits its use as an alternative to ITO in the epsilon near zero and optoelectronic applications.