Effect of Pb2Ru2O7-x (PRO) conductive interfacial layers on ferroelectric properties of Pt/Pb(Zr0.35Ti0.65)O3/Pt capacitors for nonvolatile memory applications

A conductive material, Pb2Ru2O7-x (PRO), containing Pb in a cubic structure was introduced into a Pt/PZT interface in an attempt to improve the ferroelectric properties of PZT films. PRO and PZT films were prepared by rf magnetron sputtering and chemical solution deposition, respectively. The resistivity of PRO thin films in a hybrid-type electrode (PRO/Pt) structure was approximately 35–45 μΩ·cm and the surface roughness remained constant with increasing annealing temperature. The PRO interlayers suppressed the loss of Pb in PZT layers by diffusion to the Pt/PZT interface. The increase in remanent polarization was largely dependent on the PRO interlayers inserted at the bottom-Pt/PZT interface rather than at the top-Pt/PZT interface. In addition, the leakage-current behavior of PZT films in a sandwich structure was improved substantially compared to the case of PRO interlayers only at the bottom-Pt/PZT interface. Thus, the PRO interlayers play an important role in improving the ferroelectric properties of PZT thin films for use in nonvolatile memory device applications.