Influence of Buffer Layers on Microstructural and Ferroelectric Characteristics of Sol-Gel Derived PbZr_xTi_1-xO₃ Thin Films

Abstract

Pb(Zr, Ti)O 3 (PZT) films with very thin PbTiO 3 (PT) and ( Ba 0.5 Sr 0.5 )TiO 3 (BST) buffer layers inserted between the film and Pt/Ti/ SiO 2 /Si substrate were synthesized by the sol-gel technique, and effects of variation in thickness upon microstructural and ferroelectric characteristics were investigated. Insertion of buffer layers was found to exert marked effects. PT buffer layers with thicknesses as thin as 2–4 nm yield PZT films with dense, homogeneous microstructure and good ferroelectric properties such as large remanent polarization, small coercive field and low leakage current densities. On the other hand, use of (2–4)-nm-thick BST buffer layers yields PZT films with dense microstructure and good dielectric properties such as increased permittivity, small coercive field and good leakage current characteristics. However, fatigue behavior of PZT films was not improved through insertion of PT or BST buffer layer.