Correlation between microstructure and optical transparency of PLD-derived nanostructured La₂O₃

Abstract

Lanthanum oxide (La₂O₃) thin films were synthesized using the pulsed laser deposition (PLD) method to explore their potential in optoelectronic device applications. High-purity La₂O₃ pellets were fabricated by palletisation with polyvinyl alcohol (PVA) as a binder and subsequently sintered to enhance mechanical strength. The deposition is carried out using a Nd:YAG laser (λ = 532 nm, 1000 mJ, 6 Hz) onto fluorine-doped tin oxide (FTO) substrates under a vacuum pressure of 10⁻² torr. Post-growth analyses included X-ray diffraction (XRD) to determine the crystalline structure, atomic force microscopy (AFM) for surface topography, Fourier-transform infrared spectroscopy (FTIR) and the vibrational characteristics of the La₂O₃ films were examined using Raman spectroscopy, and their optical response, including absorption and transmittance behaviour, is evaluated through UV–Vis spectroscopic analysis. Results confirmed the formation of polycrystalline films with homogeneous grain distribution and minimal surface roughness. Optical absorption studies demonstrated high transparency in the visible spectrum and revealed a direct band gap energy of 3.80 eV highlighting the suitability of La₂O₃ thin films for optoelectronic and photonic applications.