Large ferroelectric response in randomly a-axis orientated CaBi2Nb2O9 thin films by pulsed laser deposition

Abstract

CaBi₂Nb₂O₉-based (CBN-based) ferroelectric random access memory (FeRAM) has emerged as a promising candidate in the domain of data storage. Nevertheless, a comprehensive investigation into the enhancement of ferroelectric performance and the orientational configuration of FeRAM remains an area that has not been fully explored. Here, the CaBi₂Nb₂O₉/SrRuO₃/MgO (CBN/SRO/MgO) stack deposited at 750 °C shows a superior remanent polarization (P_r) of 18.43 μC/cm² under only coercive field (E_c) of 192 kV/cm. The enhancement of ferroelectric properties can be attributed to the improved crystallinity and the increased random orientational distribution, particularly the deviation from the a-axis orientation. The grain size and grain orientation distribution of the material have been quantitatively analyzed using electron backscatter diffraction (EBSD). It has been revealed that specific orientations with higher P_op values are pivotal in enhancing the polarization switching. A TEM image indicates that a layer-by-layer structure is formed of the stacked films. These findings demonstrate a novel route to designing CBN-based ferroelectric memory devices tailored for information storage and data processing, showcasing the potential for integration into advanced smart electronics of the forthcoming era.