Study of orientation effect on nanoscale polarization in BaTiO_3 thin films using piezoresponse force microscopy

摘要

We have investigated the effect of texture on in-plane (IPP) and out-of plane (OPP) polarizations of pulsed-laser-deposited BaTiO_3 thin films grown on Pt and La_(0.5)Sr_(0.5)CoO_3 (LSCO) buffered Pt electrodes. The OPP and IPP polarizations were observed by piezoresponse force microscopy (PFM) for three-dimensional polarization analyses in conjunction with conventional diffraction methods using x-ray diffraction and reflection high energy electron diffraction measurements. BaTiO_3 films grown on Pt electrodes exhibited highly (101) preferred orientation with higher IPP component whereas BaTiO_3 film grown on LSCO/Pt electrodes showed (001) and (101) orientations with higher OPP component. Measured effective d_(33) values of BaTiO_3 films deposited on Pt and LSCO/ Pt electrodes were 14.3 and 54.0 pm/V, respectively. Local piezoelectric strain loops obtained by OPP and IPP-PFM showed that piezoelectric properties were strongly related to film orientation.