Growth and properties of BiFeO3 thin films deposited on LaNiO3-buffered SrTiO3(0 0 1) and (1 1 1) substrates by PLD

BiFeO3 (BFO) films have been epitaxially grown on SrTiO3(0 0 1) and SrTiO3(1 1 1) substrates with a LaNiO3 conductive layer as a template using pulsed laser deposition. X-ray diffraction θ–2θ 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 image; BFO(1 1 1)//LNO(1 1 1)//STO(1 1 1) on SrTiO3(0 0 1) and SrTiO3(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 (2Pr) 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.