Electrical properties of Mg/La, Mg/Nb co-doped (Ba_0.7Sr_0.3)TiO₃ thin films prepared by metallo-organic deposition method

(Ba_0.7Sr_0.3)TiO₃ (BST) thin films doped with La, Nb and Mg ions along with an Mg/La, Mg/Nb codopant were prepared on Pt/Ti/SiO₂/Si substrates by the metal-organic deposition method. A decrease of grain size, dielectric constant, and leakage current with increasing doping levels was observed for all studied cases. The grain size, dielectric constant and leakage current increased with increasing annealing temperatures for specimens doped with a single dopant. However, the leakage current was reduced to a minimum for the codoped materials at the donor/acceptor compensated concentration and decreased with increasing annealing temperatures. The decreased leakage current of the codoped materials could be explained by the additional barrier height and width of the insulating layer caused by the defect dipoles around grain boundaries.