Changes of Crystal Structure and Electrical Properties with Film Thickness and Zr/(Zr+Ti) Ratio for Epitaxial Pb(Zr,Ti)O3 Films Grown on (100)cSrRuO3//(100)SrTiO3 Substrates by Metalorganic Chemical Vapor Deposition

Abstract

Lead zirconium titanate, Pb(Zr,Ti)O3 [PZT], have been intensively studied for various ferroelectric applications, and have a renewal interest due to their promising application for microelectromechanical systems (MEMS) because of their outstanding ferroelectric and piezoelectric properties. Remanent polarization (Pr) is the not only most fundamental parameter but also the practical importance for real applications to achieve high density devices. Spontaneous polarization (PS) is the expected maximum Pr value of the materials that depend on the composition, orientation and the crystallinity of Pb(Zr,Ti)O3. Thus, in an academic point of view, lots of efforts have been made to investigate PS value. However, PZT crystals with single domain are hard to be obtained, inducing a lack of direct characterization of PS values using PZT single crystal. This situation is due to c/a/c/a polydomain structure of PZT, where a domain and c domain are respective (100) and (001) oriented domains. This domain structure is the result of relaxation process of stress induced under the growth process of PZT. To achieve this purpose, we switch our idea from growth of the bulky single crystal to epitaxial films with polar axis orientation. In addition, a comprehensive and systematic characterization of ferroelectric properties of PZT films with different volume fraction of polar-axis-oriented domain is investigated. This chapter investigates the thickness and Zr/(Zr+Ti) ratio dependencies of domain structure and ferroelectric properties, and correlates physical properties, namely lattice