New Low-Temperature Processing of Metalorganic Chemical Vapor Deposition-Bi4Ti3O12 Thin Films Using BiOx Buffer Layer

We have developed a new buffer layer structure to form Bi4Ti3O12 thin films using the metalorganic chemical vapor deposition (MOCVD) method at low temperature. We confirmed that the BiO x buffer layer effectively lowers the crystallization temperature and controls the composition of Bi4Ti3O12 thin films. We have succeeded in fabricating Bi4Ti3O12 films at 400°C with good crystallinity and ferroelectric properties. Furthermore, we found that the film orientation is varied from the c-axis to the (117) preferred orientation with an increasing Bi/Ti composition ratio in thin films. The 120 nm-thick films fabricated at 400°C showed a remanent polarization P r of 1.9 µC/cm2 and a coercive field E c of 55 kV/cm for the film with c-axis preferred orientation and 8.2 µC/cm2 and 90 kV/cm for the film with (117) preferred orientation, respectively.