The effect of stress on the electrical properties of PZT thin films

We have investigated the effect of externally controlled bi-axial stress on the electrical properties of Pb(Zr,Ti)O-3 (PZT) thin films. The PZT thin films exhibited a low residual tensile stress, i.e.120 MPa. It is observed that the intrinsic residual stress of PZT films was independent of the stress state of the Pt bottom electrode, although the residual stress of the Pt bottom electrode is sensitively influenced by processing condition such as sputtering temperature. Under external compressive stress, the switching polarization or remanent polarization increased with the compressive stress. Coercive field also increased with the compressive stress. Upon applying a bi-axial stress of 300 MPa, the switching polarization increased to 40 muC/cm(2) while the PZT films with the residual tensile stress had 32 muC/cm(2). On the other hand, the polarization and coercive field was less dependent of the degree of the stress under the tensile stress. PZT thin films under the tensile stress exhibited slightly decreasing switching polarization and the coercive field with increasing the tensile stress.