Thickness dependence of material properties of epitaxial Pb(ZrxTi1-x)O3 films on Ir/(100) (ZrO2)1-x(Y2O3)x/(100)Si structures

The dependence of the material properties of heteroepitaxial (001)Pb(ZrxTi1-x)O-3 (PZT) films on film thickness were investigated. The 51- to 280-nm-thick epitaxial PZT films were deposited by reactive sputtering on (100)Ir/(100)(ZrO2)(1-x) (Y2O3), (YSZ)/(100)Si substrate structures. Although the crystalline quality of the PZT film was degraded by decreasing the thickness of the PZT film; the 30-nm-thick PZT film was epitaxially grown. The polarization-voltage(P-V) hysteresis loop of the 51-nm-thick epitaxial PZT film showed a well-saturated shape at the ac amplitude of 1.5 V. The remanent polarization P-r and the coercive field E-c decreased and increased, respectively, upon decreasing the thickness of the PZT film. The P-r value was improved by etching the surface decomposed layer of the PZT film with HNO3 solution before the formation of the top electrode. However, E-c hardly changed after etching and it is speculated that the film strain strongly influences E-c.