抄録
(111)- and (100)/(001)-oriented Pb(Zr,Ti)O3 (PZT) thin films were deposited using a chemical-solution deposition (CSD) method. For the top electrodes, IrO2 and SrRuO3 (SRO) thin films were deposited by sputtering. The ferroelectric properties and crystal structure of the (111)- and (100)/(001)-oriented PZT thin-film capacitors were evaluated. The switchable polarization (Qsw) of a (100)/(001)-oriented PZT capacitor with an SRO top electrode was lower than that with an IrO2 top electrode. The opposite trend in Qsw was observed with IrO2 and SRO top electrodes in (111)-oriented PZT capacitors. With continuous switching cycles, the Qsw of a (100)/(001)-oriented PZT capacitor with IrO2 increased continuously with an increasing number of cycles. However, there was no increase in Qsw in a (100)/(001)-oriented PZT capacitor with SRO. Transmission electron microscopy (TEM) observation showed a local epitaxial-like interface between the SRO and PZT in both the (111) and (100)/(001) orientation. However, a heterostructure was observed in the IrO2/PZT interface in both orientations. TEM also showed the existence of several 90° domains in the (100)/(001)-oriented PZT films. At the SRO/PZT(100)/(001) interface, this local epitaxial-like interface seemed to block the movement of the 90° domain wall. As a result, the Qsw was lower in a (100)/(001)-oriented PZT capacitor with SRO than that with IrO2.
