Influence of samarium oxide mixing on the structural and optical properties of tin oxide thin films prepared by pulsed laser deposition

Due to the growing demand for optoelectronic applications, it is imperative to investigate the properties of thin films and identify the most suitable ones for use in optical detectors, gas sensors, and solar cells. In a novel investigation, this work analyses the impact of samarium oxide (Sm2O3) mixing at varying weight ratios (5, 7, and 9 wt.%) on the structural, morphological, and optical properties of tin oxide (Sn) films deposited by pulsed laser deposition (PLD). XRD analysis confirmed the crystallization of a polycrystalline structure of SnO2 and SnO phases (SnOx). The crystallite size decreased from 13.1 nm to 7.2 nm with samarium content up to 7 wt.% and then increased to 11.3 nm at 9 wt.%. Top-view field emission scanning electron microscopy (FE-SEM) images revealed a broad particle size distribution that fluctuated with the Sm2O3 mixing ratio, exhibiting an average diameter of 44.53–35 nm. The incorporation of Sm2O3 elevated the film thickness to 629 nm at the maximum ratio. Atomic emissions of Sn, Sm, and O elements were identified using Energy-dispersive X-ray spectroscopy (EDX), and elemental mapping verified the homogeneous distribution of Sm into the SnOx film's surface. UV-visible transmittance spectra showed decreased transmittance from 80% to 63% at a higher Sm2O3 mixing ratio. In contrast, photoluminescence (PL) spectra exhibited a red emission peak shift, which reduced the optical bandgap from 3.4 eV to 3.15 eV. The results indicate that Sm2O3-mixed SnOx thin films exhibit adjustable characteristics appropriate for optoelectronic and catalytic applications.