Bi1.5Mg1.0Nb1.5O7/Ba0.6Sr0.4TiO3 bilayer thin films prepared by pulsed laser deposition

• Bi1.5Mg1.0Nb1.5O7/Ba0.6Sr0.4TiO3 films were prepared by pulsed laser deposition.
• The bilayered films have a high figure of merit of 61.5.
• Thickness ratio dependence of permittivity and tangent loss was discussed.
• The mechanism of the leakage current of the bilayered films was explained possibly.

Bi1.5Mg1.0Nb1.5O7/Ba0.6Sr0.4TiO3 (BMN/BST) bilayer thin films have been prepared on Au/TiOx/SiO2/Si substrates by pulsed laser deposition. The structure and electrical properties of BMN/BST bilayer thin films were investigated. X-ray diffraction results showed that the structure of BMN/BST bilayer thin films was composed of a cubic BMN pyrochlore phase and a cubic BST perovskite phase. The dielectric measurements showed that the BMN layer had played a positive role in improving the electrical properties of the thin films. With the increased thickness of BMN, the dielectric loss was significantly lowered, accompanied with a tolerable reduction of tunability. The BMN/BST bilayer thin films at a BMN/BST thickness ratio of 1 give the highest figure of merit of 61.5 and the largest commutation quality factor of 5163. In addition, the thickness effect was discussed with a series connection model of bilayered capacitors, and the calculated dielectric constant and loss tangent were obtained.