Electrical properties of W-doped (Ba0.5Sr0.5)TiO3 thin films

Ba0.5Sr0.5TiO3 (BST) thin films doped with W were deposited on LaNiO3 (LNO) electrode by RF-magnetron sputtering. The microstructure and electrical properties of BST thin films were studied as a function of W content. W-doped BST films show smoother surface and smaller grain size in comparison with the undoped BST film. With increasing W content, the dielectric constant, tunability, dissipation factor, and leakage current decrease while the figure of merit (FOM) and breakdown strength increase. Doping with the optimal content of 1% W, the BST film has a dielectric constant of 239, a tunability of 30%, a dissipation factor of 0.0066, a FOM value of 45.2, a leakage current density of 16 nA/cm2, and a breakdown strength of 500 kV/cm.