Ferroelectric Properties of MBi₄Ti₄O₁₅ (M = Sr, Pb, Ca) Thin Films

Abstract

Among the ferroelectric bismuth layered perovskites belonging to Aurivillius family, the MBi₄Ti₄O₁₅ (MBT15, M = Sr, Ca, Pb) thin films have been fabricated by a chemical solution deposition technique, and their structures and ferroelectric properties were investigated in this work. The SrBi₄Ti₄O₁₅ (SBT15) film fabricated on IrO₂ presented the highest remanent polarization (P_r) among the films in this series. It demonstrated a saturated hysteresis loop at 5 V with P_r of 19 μ C/cm² and coercive field (P_s) of 116 kV/cm. The PbBi₄Ti₄O₁₅ (PBT15) thin films were selectively controlled in c-axis and off-c-axis orientation on Pt layer by adjusting the annealing condition. The off-c-axis oriented PbBi₄Ti₄O₁₅ film demonstrated considerably higher P_r (8.7 μ C/cm²) than that of c-axis oriented film (3.7 μ C/cm²). Regardless of grain orientation, however, PBT15 films were not fatigued up to 10¹⁰ cycles under 9V application. The CaBi₄Ti₄O₁₅ (CBT15) thin films were also produced on Pt and IrO₂ electrode, respectively, by controlling the annealing condition. The CBT15 film on IrO₂ presented higher P_r (∼10.8 μ C/cm²) than that of film (∼ 6.7 μ C/cm²) on Pt.

† Present address: Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600, Korea

Keywords:

• Ferroelectric
• layered perovskite
• hysteresis loop
• fatigue
• thin film
• SrBi₄Ti₄O₁₅
• PbBi₄Ti₄O₁₅
• CaBi₄Ti₄O₁₅

ACKNOWLEDGMENT

This work has been supported by the Ministry of Information & Communication of Korea (Support Project of University ITRC Program supervised by KIPA).

Notes

† Present address: Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600, Korea