Improvements in tunability of (Ba0.5Sr0.5)TiO3 thin films by use of metalorganic chemical vapor deposited (Ba,Sr)RuO3 interfacial layers

The conducting oxide (Ba,Sr)RuO3 (BSR), which offers an appropriate match in structure with (Ba,Sr)TiO3 (BST), was investigated as an interfacial layer to obtain a high tunability and high dielectric constant in BST films. The (100)-textured BST films deposited onto BSR interfacial layers showed smoother smaller grain size than those without BSR layers. The tunability and dielectric constant of the BST films increased with increasing BSR seed layer thickness and showed ∼70% tunability and a dielectric constant of 1300 at interfacial layer of 150 Å. The tunability and dielectric constant of BST films increased nearly two times and two and a half times, respectively, as much as that of BST films without BSR interfacial layers. The higher tunability and dielectric constant have been attributed to the suppression of low-dielectric layer formation and the reduced thermal stress by lattice mismatch.