Effects of ion-beam-irradiation on morphology and densification of CeO2 films prepared by ion-beam-assisted deposition

Cerium oxide (CeO2) films were prepared by ion-beam-assisted deposition (IBAD). The films were synthesized on Si wafers by depositing CeO2 vapor under simultaneous bombardment with O-2, Ar and Xe ions in the energy range of 1.0 to 5.0 keV. Film characterizations were performed using field-emission-type scanning electron microscopy (FE-SEM) for cross-sectional observation of film morphology and film crystallization was examined by X-ray diffractometry (XRD). Rutherford backscattering spectrometry (RBS) was used for measuring the film composition and the packing density. Refractive indices of the films were measured by ellipsometry to investigate their optical properties. With increasing the transport rate ratio of ions to CeO2 vapor, the morphology of the specimens prepared with O-2 and Xe ion beams was changed from columnar to granular structure. The increase in the transport ratio also had a significant effect on the enhancement of the film densification, leading to an increase in the refractive index.