Low voltage saturation of Pb(ZrxTi1-x)O3 films on (100)Ir/(100)(ZrO2)1-x(Y2O3)x/(100)Si substrate structure prepared by reactive sputtering

The 37- to 280-nm-thick epitaxial (001)Pb(ZrxTi1-x)O3(PZT) films were deposited by reactive sputtering on the (100)Ir/(100)(ZrO2)1-x(Y2O3)x(YSZ)/(100)Si substrate structures. We investigated the film thickness and crystalline quality dependences of the ferroelectrical property of the PZT film from a viewpoint of low voltage saturation. The samples were dipped in 61% HNO3 solution prior to forming the top IrO2 electrode in order to remove the surface decomposed layer of the PZT film. By this HNO3-treatment, the remanent polarization was increased, and the squareness and symmetry of the polarization-voltage (P-V) hysteresis loop of the PZT film were improved. The P-V hysteresis loop of the 54-nm-thick HNO3-treated epitaxial PZT film was saturated at about 1.5 V. Although the coercive field Ec was increased by the HNO3-treatment, the coercive voltage was decreased by decreasing the film thickness. It was also found that Ec can be lowered by improving the crystalline quality of the PZT film.