Structural and dielectric properties of epitaxial (Ba,Sr)TiO₃ films on c-Al₂O₃ with ultra-thin TiN sacrificial template

Abstract

Using ultra-thin TiN sacrificial template, the epitaxial (Ba,Sr)TiO₃ [BST] films on c-Al₂O₃ were grown by pulsed laser deposition. TiN epitaxially grew on c-Al₂O₃ with (111) orientation, which promoted the (111) epitaxial growth of upper BST films. The obtained epitaxial BST films showed significantly larger dielectric constant compared with polycrystalline films directly deposited on c-Al₂O₃ over the wide temperature range. By inserting the TiN template, the temperature corresponding to maximum dielectric constant of BST films was shifted up by 50 K, which is mainly due to the in-plane tensile strain induced by the difference in thermal expansion coefficients of BST and c-Al₂O₃.