Fabrication and Properties of Ge-Doped (Bi,Nd)4Ti3O12 Thin Films by Chemical Solution Deposition

Abstract

Nd- and Ge-codoped Bi4Ti3O12 thin films have been fabricated by chemical solution deposition. The effects of Ge doping in (Bi,Nd)4Ti3O12 on microstructural and ferroelectric properties were investigated for the development of low-temperature fabrication of ferroelectric Bi4Ti3O12-based thin films. Bi3.35Nd0.75Ti3-xGexO12 [0≤x≤0.5] thin films were found to crystallize into the Bi4Ti3O12 phase above 600°C without forming any second phase. The crystal orientation and surface morphology of the synthesized films strongly depended on the Ge content of Bi3.35Nd0.75Ti3-xGexO12. Among various compositions of Bi3.35Nd0.75Ti3-xGexO12, Bi3.35Nd0.75Ti2.9Ge0.1O12 thin films showed excellent surface morphology and ferroelectricity regardless of the processing temperature. Furthermore, the doping of Ge below x=0.1 was found to be effective in improving the ferroelectric properties of the low-temperature-processed films. The Pr values of Bi3.35Nd0.75Ti3-xGexO12 thin films with the optimum Ge content prepared at 600°C were above 15 µC/cm2 and equal to those of the films crystallized at 700°C.