Effect of cosubstitution of La and V in Bi4Ti3O12 thin films on the low-temperature deposition

Abstract

The ferroelectricity of Bi4Ti3O12 (BIT), (Bi3.2La0.8)Ti3O12 (BLT), Bi4(Ti2.97V0.03)O12 (BTV), and (Bi3.2La0.8)(Ti2.97V0.03)O12 (BLTV) films prepared at 600 °C by metalorganic chemical vapor deposition was compared. For the BIT, BLT, BTV films deposited on (111)Pt/TiO2/SiO2/Si substrates, the ferroelectricity was not obtained even though the films consisted of a single phase. On the other hand, the BLTV films exhibited clear ferroelectricity. Furthermore, the degree of squareness of the hysteresis loops of the BLTV films was improved by changing the bottom electrode from Pt to Ir, (111)Ir/TiO2/SiO2/Si substrate; the remanent polarization and the coercive field became 8.5 μC/cm2 and 48 kV/cm, respectively. Moreover, good fatigue endurance up to 109 switching cycles was confirmed for the (Bi3.2La0.8)(Ti2.97V0.03)O12 thin film. Therefore, cosubstitution of La and V in BIT thin films is effective for lowering the deposition temperature of the film.