Growth-temperature-dependent electrical properties of Mn doping Ba0.5Sr0.5TiO3 thin films on La0.72Ca0.28MnO3 electrodes

Ba0.5Sr0.5TiO3 (BST) thin films doped with 3 mol % Mn were fabricated on La0.72Ca0.28 MnO3-coated SrTiO3(001) substrates. The effects of growth temperature and Mn doping on the lattice and electrical properties of the BST films were studied. Mn-doped BST films have rougher surfaces and larger grains than undoped BST films. Adding Mn dopants to BST films improves their dielectric constant, tunability, and leakage-current characteristics. Additionally, the degree of improvement of the electrical characteristics of the Mn-doped BST film depends strongly on the growth temperature. The higher growth temperature of the Mn-doped BST film is associated with a greater improvement in the dielectric constant and a more favorable figure of merit than in the undoped case. The tunability of the Mn-doped BST film that was deposited at 750 degrees C was enhanced from 41 to 60%; the figure of merit increased from 13 to 53, and the leakage current density was approximately one order of magnitude lower than that of the undoped film at an applied electric field of 300 kV/cm. The results demonstrate that Mn-doped BST films with appropriately controlled growth temperatures have potential for use in tunable devices.