Domain matched epitaxial growth of (111) Ba_0.5Sr_0.5TiO₃ thin films on (0001) Al₂O₃ with ZnO buffer layer

Epitaxial (111) Ba_0.5Sr_0.5TiO₃ (BST) thin films have been grown by pulsed laser deposition on (0001) Al₂O₃ substrate with ZnO as buffer layer. The x-ray ω-2θ, Φ-scan and reciprocal space mapping indicate epitaxial nature of BST thin films. The domain matched epitaxial growth of BST thin films over ZnO buffer layer was confirmed using Fourier filtered high resolution transmission electron microscope images of the film-buffer interface. The incorporation of ZnO buffer layer effectively suppressed the lattice mismatch and promoted domain matched epitaxial growth of BST thin films. Coplanar inter digital capacitors fabricated on epitaxial (111) BST thin films show significantly improved tunable performance over polycrystalline thin films.