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- x Nb x O12 (BNTN x , 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 BNTN x thin films were investigated. A low-concentration substitution with Nb ions in BNTN x can greatly enhance its remanent polarization (2 P r) and reduce the coercive field (2 E c) compared with those of Bi4Ti3O12 (BIT) thin film. The highest 2 P r (71.4 μC/cm2) was observed in the BNTN0.03 thin film when the 2 E c was 202 kV/cm. Leakage currents of all the films were on the order of 10-6 to 10-5 A/cm2, and the BNTN0.03 thin film has a minimum leakage current (2.1 × 10-6 A/cm2) 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°C.