Enhanced oxygen sensing in ZrO2 thin films via atomic layer deposition by post-deposition annealing

Zirconium dioxide (ZrO 2 ) thin films were grown via atomic layer deposition (ALD) and subjected to annealing at temperatures from 700 °C to 900 °C. The effects of annealing on the optical, structural, and gas-sensing properties of the films were investigated using spectroscopic ellipsometry, UV–visible spectroscopy, atomic for microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) and cathodoluminescence (CL). A decrease in surface roughness with increasing annealing temperature resulted in a lower refractive index due to reduced light scattering, while the bandgap remained relatively stable. XPS confirmed the presence of oxygen vacancies across all conditions, which underwent structural reorganization, as evidenced by PL and CL, where the formation of F centers was linked to increased gas sensitivity. Gas-sensing measurements demonstrated that reduced surface roughness improved the selectivity and stability of catalytic active sites for O 2 molecules. These findings highlight that precise control of annealing conditions can optimize ZrO 2 films for advanced gas-sensing applications by tuning surface morphology and defect properties.