Large remanent polarization of cerium-modified bismuth–titanate thin films for ferroelectric random access memories

Abstract

Cerium-substituted Bi4Ti3O12 (Bi3.4Ce0.6Ti3O12) thin films were prepared by using metal-organic decomposition method. Ferroelectric cerium-substituted Bi4Ti3O12 thin films were fabricated by spin coating onto a Pt/Ti/SiO2/Si substrate. The structure and morphology of the films were characterized using x-ray diffraction and scanning electron microscopy. The Bi3.4Ce0.6Ti3O12 (BCeT) thin films, which were annealed from 550 to 700 °C for 1 h, showed a perovskite phase and dense microstructure. The BCeT thin films annealed at temperature as low as 550 °C become crystallized and exhibit a polycrystalline structure with ferroelectric properties. The 200-nm-thick BCeT thin films annealed at 700 °C showed a large remanent polarization (2Pr) of 62.1 μC/cm2 at an applied voltage of 10 V and exhibited a fatigue-free behavior up to 5×1010 switching cycles at a frequency of 100 kHz. These experimental results are thought to be promising to use cerium-substituted Bi4Ti3O12 thin films as capacitors of ferroelectric access memory applications.