The influence of an extrinsic interfacial layer on the polarization of sputtered BaTiO3 film

As an origin of degradation of remnant polarization in Pt∕BaTiO3∕Pt capacitor structure, an interfacial layer formed at the interface of BaTiO3 film and a Pt bottom electrode is considered. BaTiO3 films were deposited on two types of bottom electrodes (La0.5Sr0.5CoO3 and Pt) by the radio frequency magnetron sputtering method and both capacitors showed a microstructural similarity with strong preferred orientations. However, a Pt∕BaTiO3∕La0.5Sr0.5CoO3 capacitor exhibited a saturated hysteresis loop with the remnant polarization (2Pr) of 6μC∕cm2, and for the Pt∕BaTiO3∕Pt structure, the polarization-voltage curve revealed a linear dielectric characteristic. From a cross-sectional high-resolution transmission electron microscope analysis of the Pt∕BaTiO3∕Pt capacitor showing the linear dielectric property, an interfacial layer with an amorphous structure as well as a multidomain structure in the interior of the BaTiO3 film were observed. It is concluded that the interfacial layer might help degradation of polarization and its origin can be classified as being extrinsic.