Fabrication and Electrical Properties of Strain-Modulated Epitaxial Ba[sub 0.5]Sr[sub 0.5]TiO[sub 3] Thin-Film Capacitors

(BST) epi layers thick with different magnitudes of lattice distortion were fabricated by growing films on various perovskite oxide electrodes. The variations in the misfits between the BST and the bottom electrodes enable the strain manipulation of these BST epi layers. The thick BST epi layer on the -coated (STO) substrate is almost completely constrained by the bottom electrode. The thick BST epi layers are partially constrained on the Nb-doped STO, -coated STO, and -coated STO substrates. A suitable degree of lattice distortion of the BST epi layers is required to obtain a large dielectric constant; this fact is consistent with expectations based on the softening of the soft mode phonon. Variations to the electrical characteristics of the BST epi layers were considered with reference to changes in the degree of the lattice distortion of the BST epi layers.