Ferroelectric Properties of Sol-Gel-Derived PbTiO₃ Type Thin Films

Abstract

The degradation of ferroelectric properties with decreasing film thickness is a common problem of PbTiO 3 type ferroelectric thin films. We suspected that this degradation was caused mainly by oxygen vacancies that diffused from the film surface through the grain boundaries during firing. Thus we have been attempting Al 3+ substitution for Ti 4+ in PbTiO 3 using a sol-gel method. In this study, the relationship between the ferroelectric properties of Pb(Ti 0.85 Al 0.15 )O 3- x thin films and the firing conditions in the thin film preparation process was investigated. The 0.14-µ m- thick Pb(Ti 0.85 Al 0.15 )O 3- x films fired at 700° C for 15 min in air exhibited good ferroelectric properties. For these firing conditions, the dielectric constant, remanent polarization and coercive field were ε =356, Pr=9 µ C/cm 2 and Ec=84 kV/cm, respectively.