Composition Dependence in BiFeO₃ Film Capacitor with Suppressed Leakage Current by Nd and Mn Cosubstitution and Their Ferroelectric Properties

Abstract

(Nd,Mn)-cosubstituted BiFeO3 (BFO) films with various Nd and Mn compositions were fabricated on a Pt/SrTiO3(100) substrate by pulsed laser deposition. X-ray diffraction patterns and atomic force microscopy images indicated that the suppression of impurity phases and a smooth surface morphology were realized by Nd substitution in the BFO films. Furthermore, by combining with Nd substitution, a small amount of Mn substitution in BFO films is effective for reducing the leakage current density by three orders of magnitude compared with that of a BFO film capacitor. The polarization vs electric field (P–E) curves showed a strong dependence of measurement frequency in the range of 0.1–2 kHz, and well-saturated P–E hysteresis loops were observed at 20 kHz at room temperature. The remanent polarization and coercive field at a maximum electric field of 1.9 MV/cm were approximately 70 µC/cm2 and 0.32 MV/cm, respectively.