Dielectric properties of epitaxial Ba0.6Sr0.4TiO3 films on SiO2∕Si using biaxially oriented ion-beam-assisted-deposited MgO as templates

We have epitaxially deposited Ba0.6Sr0.4TiO3 (BST) thin films on SiO2∕Si substrates using pulsed laser deposition by introducing biaxially oriented ion-beam-assisted-deposited MgO as templates. The structural properties of the BST films were strongly affected by the crystallinity of the templates. The dielectric loss of the BST film was found to decrease as its in-plane texture alignment was improved. As a result, a relatively larger figure of merit K value, defined as tunability∕loss, was obtained for the films with better in-plane crystallinity. The K factor ranged between 7.5 and 3.5 when the in-plane alignment of the MgO templates was varied from 5.0° to 10.5°. This work demonstrates that the crystalline quality of the template layers plays a critical role in monolithic integration of BST with SiO2∕Si for frequency agile devices.