Microstructural and electrical properties of BaTiO3 epitaxial films on SrTiO3 substructures with a LaNiO3 conductive layer as a template

Abstract

BaTiO3 (BTO) films have been epitaxially grown on SrTiO3(001) and SrTiO3(111) substrates with a LaNiO3 conductive layer as a template using pulsed laser deposition. X-ray diffraction θ–2θ and ψ scanning reveal that the epitaxial relationship for these samples fabricated at 600 °C and 700 °C are BTO[001]//LNO[001]//STO[001] and BTO[111]//LNO[111]//STO[111], respectively. Ex situ reflective high energy electron diffraction patterns also clearly confirm this epitaxial relationship. The epitaxial growth can be more easily realized on LNO-inserted STO(001) substrates at a relatively wide range of temperatures. From C–V measurements, the dielectric constant of the epitaxial (001)BTO film is determined as 159.5, which is larger than the value 89.6 of (111)BTO film. The remanent polarization (2Pr) of the epitaxial BTO(001) thin film on the LNO-coated (001)STO substrate is 39.8 µC cm−2, which is much larger than that of the BTO(111) film on the LNO-coated STO(111) substrate. The result is also consistent with the direct observation made by piezoresponse force microscopy investigation. Thus, with the epitaxial LNO electrode template layers, the epitaxial BaTiO3(001) ferroelectric films exhibit high-quality structure and good electrical properties.