Energy Storage Characteristics of BiFeO(3)/BaTiO(3) Bi-Layers Integrated on Si

BiFeO(3)/BaTiO(3) bi-layer thick films (~1 μm) were deposited on Pt/Ti/SiO(2)/(100) Si substrates with LaNiO(3) buffer layers at 500 °C via a rf magnetron sputtering process. X-ray diffraction (XRD) analysis revealed that both BiFeO(3) and BaTiO(3) layers have a (00l) preferred orientation. The films showed a small remnant polarization (P(r) ~ 7.8 μC/cm(2)) and a large saturated polarization (Ps ~ 65 μC/cm(2)), resulting in a slim polarization-electric field (P-E) hysteresis loop with improved energy storage characteristics (W(c) = 71 J/cm(3), η = 61%). The successful “slim-down” of the P-E loop from that of the pure BiFeO(3) film can be attributed to the competing effects of space charges and the interlayer charge coupling on charge transport of the bi-layer film. The accompanying electrical properties of the bi-layer films were measured and the results confirmed their good quality.