Effect of poling treatment on e₃₁ piezoelectric constant of sputtered PZT thin films

Abstract
Pb(Zr,Ti)O₃ (PZT) is a material of great interest due to its intrinsic properties : ferroelectricity and consequently piezoelectricity. It is very attractive in deformation sensors or transducers of surface and bulk acoustic wave and also in micromechanical applications. In thin film form, there has been no systematic study of the poling effect on the piezoelectric properties of PZT ; our system of measurement of the direct piezoelectric effect allows it. Films of thicknesses in range of 3 µm are studied. The piezoelectric response of films has been evaluated function of the poling treatment and we have registered the piezoelectric hysteresis loop. They were initially piezoelectric which causes the offset of the piezoelectric hysteresis loops. We discuss here the time necessary to polarize the film with a dc bias and show that an efficient poling of the films can be achieved at room temperature under the field of 120 kV/cm. The maximum and the remanent piezoelectric constants, measured in this configuration are respectively -2.5 C/m² and -2 C/m².