THE EFFECT OF SEEDING LAYERS ON FERROELECTRIC PROPERTIES OF PTZT THIN FILMS

ABSTRACT

In this paper, the TiO_x and PbO seeding layers have been used to study the influence of Pb_1.08(Ta_0.005Zr_0.3Ti_0.695)O₃ (PTZT) thin films on a stabilized Pt/Ti/SiO₂/Si bottom electrode. The PTZT and PbO/PTZT/PbO XRD measurements show that the major perovskite orientations (100), (110) and (111) have been found together with pyrochlore and the TiO_x/PTZT/TiO_x XRD measurement displays strong (111)-preferred orientation. The best ferroelectrics values and fatigue properties have been measured for the sample TiO_x/PTZT/TiO_x film. And strongly asymmetric polarization hysteresis loops are observed in the sample PbO/PTZT/PbO. We take the view that the origin of the hysteresis loop offsets and asymmetry is caused by a strong electric field within a thin surface layer in which the ferroelectric polarization is smaller or even absent compared to the bulk of the film. The fatigue characteristic of PTZT thin films suggests that the TiO_x and PbO seeding layers alleviate the accumulation of oxygen vacancies near the interface which has been proposed as a primary cause of fatigue in lead base perovskite thin films.

Keywords:

• PTZT
• seeding layer
• ferroelectric
• asymmetric polarization hysteresis loop

ACKNOWLEDGMENTS

This work is supported by the Key program of National Nature Science Foundation of China, No. 90407023.