Measurement of transverse piezoelectric properties of PZT thin films

Transverse piezoelectric properties of Pb(Zr, Ti)O-3 (PZT) films were estimated using a simple measuring method we developed. The c-axis oriented PZT films were epitaxially grown on Pt/MgO substrates, while the polycrystalline PZT films with the preferential orientation of <111> were deposited on Pt/Ti/Si substrates using rf sputtering technique. The piezoelectric characteristics of the PZT films with different crystalline structures were evaluated by the tip deflection of the unimorph cantilevers of the strip specimen just cleaved out from the substrates. The PZT films on MgO substrates showed excellent linear piezoelectric deflection to the applied voltage with the stable piezoelectric coefficient e(31) of -4.7 to -4.9 C/m(2) which is caused by the ideal lattice motion of the single domain structure. On the other hand, the PZT films on Si substrates showed large hysteresis of the deflection and the value of e(31) ranged from -4.3 to -7.5 C/m(2) according to the applied voltage. The non-linear as well as large piezoelectric response of the PZT films on Si is similar to conventional bulk PZT ceramics, indicating that the reorientation of domains whose polar axes are not parallel to the electric field is superimposed on the lattice motion. (C) 2003 Elsevier B.V. All rights reserved.