Ferroelectric Properties of Bi4Ti3O12 Thin Films Prepared on TiO2 Anatase Layer

Abstract

Undoped Bi4Ti3O12 (BIT) thin films with a TiO2 anatase buffer layer were prepared on the Pt/Ti/SiO2/Si substrates by metalorganic chemical vapor deposition. The BIT thin film with the TiO2 anatase buffer layer prepared at 500°C exhibited highly a- and b-axis-oriented BIT single phases, although the BIT thin film with no buffer layer exhibited a c-axis orientation. The interface between the BIT thin film and the substrate was very smooth. The BIT thin film consisted of small grains and exhibited a good P-E hysteresis loop. The ferroelectricity of the BIT thin film with the TiO2 anatase buffer layer strongly depends on the thickness ratio of the BIT thin film to the TiO2 anatase layer, indicating that the TiO2 anatase buffer layer acts not as barrier layer but as an initial nucleation layer of the BIT thin film. When the thickness ratio is fixed at [(BIT)/(TiO2)]=15, the remanent polarization (Pr) and the coercive field (Ec) were 2Pr=81.6 µC/cm2 and 2Ec=250 kV/cm, respectively. The dielectric constant (εr) was 160.