Laser-induced non-linear optical properties of transparent conducting Sn_1-xNi_xO₂ thin films prepared by spray pyrolysis for optoelectronic device application

This research work focuses on the influence of Nickel (Ni) (0–10 wt.%) doping on structural, surface, linear, and non-linear optical parameters of Tin oxide thin films. The above thin films were deposited on glass substrate using the spray pyrolysis technique. A crystalline thin film with tetragonal structure was confirmed from X-ray diffraction. Intensity of the prominent peak (110) decreased with increase in doping concentration. Both Scherrer and the W–H plot methods were considered to determine the crystallite size of Sn_1-xNi_xO₂ thin film. Formation of cluster-like structures was visible using the FESEM results. Confirmation of elemental composition was done using EDAX. A decrease of surface roughness with increasing doping concentration was detected. Doping on Nickel brought changes in the transmittance of the thin film from 84 to 80% for lower doping concentrations in the visible region. The PL studies depicted peaks due to contributions of both Sn⁴⁺ ions and oxygen vacancies. Near white light emission was observed due to the presence of the defects. Third-order non-linear studies were carried using the Z-Scan, and all the deposited samples showed non-linearity. Reverse saturable absorption (RSA) was observed in the deposited thin film. The third-order non-linear susceptibility were seen to range to be suitable for optical limiting applications. Hence, the spray pyrolysis-deposited thin films are found to be suitable for optical limiters.