Growth and properties of BiFeO 3 thin films deposited on LaNiO 3-buffered SrTiO 3(0 0 1) and (1 1 1) substrates by PLD

Abstract

BiFeO 3 (BFO) films have been epitaxially grown on SrTiO 3(0 0 1) and SrTiO 3(1 1 1) substrates with a LaNiO 3 conductive layer as a template using pulsed laser deposition. X-ray diffraction θ–2 θ and Φ scanning revealed that the epitaxial relationship is BFO[1 0 0]//LNO[1 0 0]//STO[1 0 0]; BFO(0 0 1)//LNO(0 0 1)//STO(0 0 1) and BFO [ 11 2 ¯ ] / / LNO [ 11 2 ¯ ] / / STO [ 11 2 ¯ ] ; BFO(1 1 1)//LNO(1 1 1)//STO(1 1 1) on SrTiO 3(0 0 1) and SrTiO 3(1 1 1) substrates, respectively. The epitaxial relationship was also confirmed by ex situ reflective high-energy electron reflection (RHEED). From P– E measurements, both samples showed typical ferroelectric hysteresis loops, indicating good electrical properties. Furthermore, it was found that the remanent polarization (2 P r) under the same applied electrical field of the epitaxial BFO(1 1 1) thin film on the LNO-coated (1 1 1) STO substrate is much larger than that of the BFO(1 0 0) film on the LNO-coated STO(1 0 0) substrate. The larger polarization of BFO(1 1 1) films may be caused by that the easy polarization axis lays close to [1 1 1] direction, indicating the anisotropic ferroelectric property for BFO films. Thus, with the epitaxial LNO electrode template layers, the epitaxial BFO films exhibit high-quality structure and good electrical properties.