Epitaxial BiFeO_3 Multiferroic Nanoislands Fabricated by Chemical Assembled Method and Their Characterization

Epitaxial BiFeO_3 nanoislands were fabricated on SrTiO_3(100) single crystal and Nb-doped SrTiO_3(100) single crystal substrates by chemical assembled method.Their phase structure and morphology were characterized by X-ray diffraction,scanning electron microscope,and atomic force microscope,respectively.The results showed that epitaxial BiFeO_3 nanoislands could be obtained by post-annealing in the temperature range of 650-800℃,and their lateral sizes were in the range of 50-150 nm and height of 6-12 nm.With increasing the post-annealing temperatures, the morphology of BiFeO_3 nanoisland in the(100) growth plane evolved from tri-angle to square,and then to long rod shape.By using piezo-force microscope,ferroelectric characteristics of single epitaxial BiFeO_3 nanoisland grown on Nb-doped SrTiO_3(100) single crystal substrates with lateral size of about 50 nm and height of 12 nm was characterized.The results demonstrated that fractal ferroelectric domains existed in the single BiFeO_3 nanoisland,and self-biased polarization effect was also observed within the nanoisland.This phenomenon was ascribed to interfacial stress caused by the lattice misfit between the BiFeO_3 nanoisland and the SrTiO_3 single crystal substrate.