Ferroelectric polarization and surface charge trap of epitaxial SrBi2Ta2O9 and PbZr0.53Ti0.47O3 thin films

Epitaxial ferroelectric thin films of SrBi2Ta2O9 (SBT) and PbZr0.53Ti0.47O3 (PZT) were deposited on epitaxial La0.5Sr0.5CoO3(LSCO)/(100) LaAlO3 substrate by pulsed laser deposition. The PZT thin film showed c-axis oriented epitaxial growth. On the SBT thin films, perpendicular arrangement of rectangular grains was observed with (001) and relatively larger (220) X-ray diffraction peaks than other SBT peaks. Observed by kelvin probe force microscopy (KFM), when a high electric field is applied on a cantilever, a charge trap is a dominant effect than a ferroelectric polarization resulting from the increase of the surface charge trap due to high electric field and saturation of remanent polarization. By properly biasing low voltage, the polarization effect is larger than the surface charge trap effect and the sign of the surface potential is reversed indicating a dominant contribution from the ferroelectric polarization.