Stabilisation of Cubic ZrO2 Thin Films Synthesized by Spray Pyrolysis: Influence of Cu Doping on Structural and Optical Properties

Nano-structured cubic Zirconium oxide (ZrO2) thin films have garnered considerable attention for its versatile use in gas sensors, fuel cells, nuclear reactors, and MOSFET gate dielectrics. In the present study, a facile Spray Pyrolysis technique was used to deposit pure and 2-8% Cu-doped Zr02 thin films annealed at 500° C for 1 hour and their structural and optical properties were investigated. All films exhibited single phase cubic polycrystalline structure that predominantly oriented along the (111) plane. The lattice constant of pure ZrO2 thin films is found to be 5.107 A which slightly decreases in Cu-doped films due to the incorporation of smaller Cu
²
+ ions into larger Zr
⁴
+ site. The crystallite sizes of the films were under 42 nm. All thin films exhibited ≥72 % transparency in the visible region with a maximum of 76.2% with 8% Cu doping. Pure ZrO2 thin films showed a bandgap of 3.96 eV which increased to 3.98 eV for 4 % Cu doping before returning to the initial value for the 8 % Cu-doped film. The unique characteristics of zirconia in its cubic stabilized form make it an ideal material for various photonic-enabled technologies.