Ion beam-assisted pulsed laser deposition of (Ba,Sr)(Ti,Zr)O3 films on Pt-Si substrates

Ion beam-assisted pulsed laser deposition with an Ar-oxygen ion mixture was used to prepare Ba0.6Sr0.4Ti0.7Zr0.3O3 (BSTZ) thin films on Pt-coated Si substrates. The ion beam with an anode voltage of 600 V was effective to reduce the thermal budget, i.e., to achieve similar crystallinity with approximately 100 deg. C lower deposition temperature compared to the cases without ionization. It was revealed that the dielectric properties (relative dielectric constant εr and its electric field tunability), out-of-plane lattice parameter of (001)-oriented grains (a001), and the existence of (110)-oriented grains are correlated with one another. Elongation of a001 was suppressed, resulting in large εr values comparable with that of a ceramic bulk of the same composition, in the BSTZ films that contain (110)-oriented grains. Less volume of amorphous BSTZ region is supposed to be playing an important role for the bulklike properties of these BSTZ films.