Synthesis and properties of Ba(Ti,Sn)O₃ films by e-beam evaporation

Ba(Ti,Sn)O₃ thin films, for use as dielectrics for MLCCs, were grown from Sn doped BaTiO3 sources by e-beam evaporation. The crystalline phase, microstructure, dielectric and electrical properties of films were investigated as a function of the (Ti+Sn)/Ba ratio. When BaTiO₃ sources doped with 20-50 mol% of Sn were evaporated, BaSnO₃films were grown due to the higher vapor pressure of Ba and Sn than of Ti. However, it was possible to grow the Ba(Ti,Sn)O₃ thin films with ≤ 15 mol% of Sn by co-evaporation of BTS and Ti metal sources. The (Ti+Sn)/Ba and Sn/Ti ratio affected the microstructure and surface roughness of films and the dielectric constant increased with increasing Sn content. The dielectric constant and dissipation factor of Ba(Ti,Sn)O₃ thin films with ≤ 15 mol% of Sn showed the range of 120 to 160 and 2.5-5.5% at 1 KHz, respectively. The leakage current density of films was order of the 10^-9-10^-8A/cm² at 300 KV/cm. The research results showed that it was feasible to grow the Ba(Ti,Sn)O₃ thin films as dielectrics for MLCCs by an e-beam evaporation technique.