Electric field-tunable BaxSr1-xTiO3 films with high figures of merit grown by molecular beam epitaxy

We report on the dielectric properties of BaxSr1-xTiO3 (BST) films grown by molecular beam epitaxy on epitaxial Pt bottom electrodes. Paraelectric films (x <= 0.5) exhibit dielectric losses that are similar to those of BST single crystals and ceramics. Films with device quality factors greater than 1000 and electric field tunabilities exceeding 1: 5 are demonstrated. The results provide evidence for the importance of stoichiometry control and the use of a non-energetic deposition technique for achieving high figures of merit of tunable devices with BST thin films. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773034]