Dielectric enhancement and, Maxwell-Wagner effects in polycrystalline ferroelectric multilayered thin films

Dielectric enhancement was observed in polycrystalline BaTiO3/Ba0.6Sr0,4TiO3 multilayered thin films deposited layer-by-layer on Pt/Ti/SiO2/Si substrates via pulsed laser deposition. The dielectric constant of the films was enhanced more than four times with the decrease of the individual layer thickness down to 30 nm, while the dielectric loss was kept at a low level comparable to that of the solid solution Ba0.8Sr0.2TiO3 thin films. The Maxwell-Wagner model is proposed to explain the experimental data, which can predict both the dielectric enhancement and frequency dependence when the individual layer thickness is more than 40 nm.