Plasma-ion-assisted deposition of HfO₂ films with low UV absorption

HfO2 films were fabricated by plasma-ion-assisted deposition of electron beam evaporation (PIAD-EBE) for low absorption applications in UV. The optical, structural and composition properties of the deposited HfO2 films were systematically investigated to evaluate the influence and its mechanism of four kind process parameters. The results revealed that the crystal orientation of the monoclinic phase in the HfO2 films was very sensitive to momentum transfer originating from the plasma ions or the substrate temperature. Besides, the evolution of the crystal orientation with momentum transfer showed a strong correlation with the refractive index and its inhomogeneity in the HfO2 films. An optimized HfO2 film with very low extinction coefficients and high refractive index, which was critical to UV applications such as HR mirrors and solar-blind filters, was obtained.