Effects of Nb Content on the Ferroelectric and Dielectric Properties of Nb/Nd-Co-doped Bi4Ti3O12 Thin Films

Nd/Nb-co-substituted Bi3.15Nd0.85Ti3-xNbxO12 (BNTNx , x = 0.01, 0.03, 0.05 and 0.07) thin films were grown on Pt/Ti/SiO2/Si (100) substrates by chemical solution deposition. The effects of Nb content on the micro-structural, dielectric, ferroelectric, leakage current and capacitive properties of the BNTNx thin films were investigated. A low-concentration substitution with Nb ions in BNTNx can greatly enhance its remanent polarization (2P(r)) and reduce the coercive field (2E(c)) compared with those of Bi4Ti3O12 (BIT) thin film. The highest 2P(r) (71.4 mu C/cm(2)) was observed in the BNTN0.03 thin film when the 2E(c) was 202 kV/cm. Leakage currents of all the films were on the order of 10(-6) to 10(-5) A/cm(2), and the BNTN0.03 thin film has a minimum leakage current (2.1 x 10(-6) A/cm(2)) under the high electric field (267 kV/cm). Besides, the C-V curve of the BNTN0.03 thin film is the most symmetrical, and the maximum tunability (21.0%) was also observed in this film. The BNTN0.03 thin film shows the largest dielectric constant and the lowest dielectric loss and its maximum Curie temperature is 410 +/- 5 degrees C.