Impact of oxygen flow rate and annealing on the structural and optical properties of HfO2 thin films

This work presents an organized study of oxygen flow rate and annealing temperature optimization for reactive RF magnetron sputtering-based HfO
2
thin film deposition. The structural analysis shows that as-deposited films exhibit an amorphous structure with oxygen flow rate of 10 sccm. On the other hand, polycrystalline monoclinic structure revealed for higher oxygen flow (>10 sccm). Increasing the annealing temperature enhances the intensity of the diffraction peaks. The crystallite grain size grows from 15 to 28 nm with an increase in oxygen partial pressure. Optical-transmittance enhances from 80% to 90% owing to increased oxygen flow. Following annealing at 600°C with varying oxygen flow rates such as 10, 15, and 20 sccm, the films exhibited higher indirect bandgap energies of 5.53 eV, 5.85 eV, and 6.03 eV, respectively. These results highlight the significance of tailoring oxygen flow rate and annealing temperature to control the structural and optical characteristics of HfO
2
thin films for advanced semiconductor device applications.