Low Voltage Saturation of Pb(Zr_xTi_1-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(Zr x Ti 1- x )O 3 (PZT) films were deposited by reactive sputtering on the (100)Ir/(100)(ZrO 2 ) 1- x (Y 2 O 3 ) 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% HNO 3 solution prior to forming the top IrO 2 electrode in order to remove the surface decomposed layer of the PZT film. By this HNO 3 -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 HNO 3 -treated epitaxial PZT film was saturated at about 1.5 V. Although the coercive field E c was increased by the HNO 3 -treatment, the coercive voltage was decreased by decreasing the film thickness. It was also found that E c can be lowered by improving the crystalline quality of the PZT film.