Dielectric and ferroelectric properties of Bi2Ti2O7 thin films with (111) orientation

Abstract

Transparent and crack-free Bi2Ti2O7 thin films with strong (111) orientation were successfully prepared on n-Si(100) by chemical solution deposition (CSD) using bismuth nitrate and titanium butoxide as starting materials. The growth procedure of the Bi2Ti2O7 thin films is discussed in this paper. The surface morphology of the Bi2Ti2O7 film was investigated by using Electric Force Microscope (EFM), and the crystallization of the films was studied by x-ray diffraction (XRD). Bismuth titanate thin film prepared on (100) silicon substrate showed strong (111) orientation. Its dielectric properties and the current-voltage (I-V) characteristics were measured. The dielectric constant of the Bi2Ti2O7 thin films vs. frequency in the temperature range of 100–800°C were studied. The dielectric constant and the dielectric loss for Bi2Ti2O7 are 118 and 0.07 respectively at 100 KHz. For the Bi2Ti2O7 films with 0.4 μrn in thickness annealed at 580°C for 40 minutes, their leakage current density is 4.06×10−7 A/cm2 at an voltage of 15 V. The ferroelectric phase transition has been observed distinctly and the Curie temperature was determined for the Bi7Ti2O7 ceramic films. Capacitance vs. temperature was measured from 27°800°C at 1KHz. 10KHz, 100KHz and 1MHz.