Self-buffered BaxSr1−xTiO3 films by sol–gel and RF magnetron sputtering method

BaxSr1−xTiO3 (BST) films are fabricated by sol–gel and RF (radio frequency) magnetron sputtering method. A buffer layer with columnar grains by sol–gel method is introduced to improve the dielectric anomaly in BST films. We find that the presence of buffer layer can increase the differential dielectric constant against temperature in sol–gel derived BST films while not so with sputtered films. We explain this by an ‘expanded layer thickness model’ and an unstable crystallized surface, respectively. The obtained (dε/ε) dT is up to 6% around 11 °C by the sol–gel method.