Dielectric enhancement in interface-modified BaTiO3/SrTiO3 multilayered films prepared by pulsed laser deposition

Pulsed-laser-deposited polycrystalline BaTiO3/SrTiO3 multilayered films on Pt/Ti/SiO2/Si substrates have been fabricated with interfacial modification through lowering the oxygen pressure during the time interval in between two adjacent depositions. It is found that the formation of the heterolayered structure is essential to get the dielectric enhancement. Such heterolayered films have large dielectric constant of 1201 with a loss tangent below 0.1 at 10 KHz. This is about two times that of the identically prepared Ba0.5Sr0.5TiO3/Ba0.5Sr0.5TiO3 homolayered and uniform Ba0.5Sr0.5TiO3 films. The enhancement of dielectric properties is attributed to the presence of the interfacial regions with controllable space charges due to the formation of oxygen vacancies at lower oxygen pressure.