Study on the Structural and Optical Properties of CuO Thin Films Mixed with La2O3 Deposited using Pulsed Laser Deposition for Future Optoelectronic and Gas Sensing Devices Applications

The mix of thin metal oxide coatings with rare earth elements demonstrates great potential for improving structural and optical properties in advancing optoelectronic devices and gas sensors. This study investigated the impact of varying weight ratios mixing of lanthanum oxide (La₂O₃) on copper oxide (CuO) thin films' structural, topographic, microstructural, and electronic transition characteristics. The characteristics of films developed via pulsed laser deposition were examined utilizing X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy and atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and UV-Vis spectroscopy analysis. According to the structural analysis, the polycrystalline copper oxide film crystallized with a dominating peak towards the (111) diffraction peak. The dominant peak intensity decreased as the lanthanum oxide content increased, and the crystal size reduced from 19 to 17.4 nm. The elemental analysis confirmed the presence of O, Cu, and La elements and no other EDX emission peaks corresponding to additional elements or impurities. The as-deposited CuO film had a wide nano-grain distribution, with an average grain size of 100 nm and an average RMS of 3.7 nm. In contrast, the La2O3 mixed-CuO samples showed a decrease in average grain size and increased RMS to 4.9 nm for the largest La2O3 mixing ratio. The optical analysis verified a reduction in the CuO absorbance spectrum and a blue shift in the absorption edge with an increasing mixing ratio of La2O3, raising the optical energy gap from 2.25 eV to 2.85 eV. The results indicate that the mixing of La₂O₃ substantially modifies the structural and optical characteristics of CuO thin films, rendering the developed films suitable candidates for gas sensing and optoelectronic applications