A comprehensive investigation on thickness dependent intrinsic properties of spin coated CeO2 thin films

This report focuses on the thickness dependent variation of intrinsic properties in nanoscale spin-coated cerium oxide (CeO 2 ) thin films on soda lime glass substrates. Structural analysis through XRD and Raman spectroscopy confirmed the formation of the desired cubic phase and the presence of structural defects. Detailed Raman analysis revealed the existence of intrinsic defects and the combined role of Fano resonance and phonon confinement effects. SEM and AFM studies revealed a smooth and uniform surface morphology with well-distributed grains. XPS analysis confirmed the presence of both Ce 4+ and Ce 3+ oxidation states, with a reduced Ce 3+ content in the 10-layer sample, indicating fewer oxygen vacancies. Optical analysis showed high transparency, slight variation in bandgap, and Urbach energy calculations confirmed the presence of defects. Photoluminescence measurements showed a broad emission between 350–500 nm, indicating the presence of intrinsic defects. Spectroscopic ellipsometry measurement and electrical measurement were also added to observe the influence of thickness on the refractive index and resistivity of thin films. • XRD confirmed a cubic fluorite crystal structure, with improved crystallinity observed in films with 10 spin-coated layers. • Raman analysis revealed the existence of intrinsic defects and the combined role of Fano resonance and phonon confinement effects. • XPS revealed both Ce 4+ and Ce 3+ states, with reduced oxygen vacancies for thin films with 10 layers. • High optical transparency with a direct bandgap between 3.52 and 3.57 eV was observed. • Spectroscopic ellipsometry showed a refractive index range of 2.18–2.22 at 633 nm and low extinction coefficients.