Abstract: Epitaxial BiFeO₃ nanoislands were fabricated on SrTiO₃ (100) single crystal and Nb-doped SrTiO₃ (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 BiFeO₃ 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 BiFeO₃ 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 BiFeO₃ nanoisland grown on Nb-doped SrTiO₃ (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 BiFeO₃ 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 BiFeO₃ nanoisland and the SrTiO₃ single crystal substrate.

Key words: BiFeO₃, epitaxial nanoislands, chemical assembled method, structure and physical property