POLARIZATION CHANGE OF PZTN FERROELECTRIC THIN FILMS UNDER UNIFORM IN-PLANE TENSILE STRESS

ABSTRACT

We applied uniform in-plane tensile stress on PZTN ferroelectric thin films of 130 nm in thickness, using a four-point bending test rig and measured the corresponding changes in polarization and leakage current. An initial polarization hysteresis loop, which is different from the repeatable one after repetitive loadings, was observed. In the range of the tensile stress we applied (up to 150 MPa), the remnant polarization decreased linearly in reference to the repeatable hysteresis at a rate of ∼ 0.002 μC _cm ^-2 MPa ^-1 which is more than two orders smaller than that of bulk PZT materials.The corresponding coercive voltage increased very little(< 0.02V),but the leakage current at small voltages showed a sudden increase during the loading process, changing from an ohmic behaviour (n = 1) when the stress is < 53 MPa to a sub-linear one (n =0.4)forI ∼Vⁿ when the stress is > 109 MPa.

ACKNOWLEDGMENT

This work is partly funded by EPSRC under grant number GR/S98412/01.