中文摘要：

采用化学自组织方法在SrTiO3（100）及Nb-掺杂SrTiO3000）单晶衬底上制备了外延BiFeO3纳米岛，并利用X射线衍射、扫描电子显微镜和原子力显微镜对纳米岛的相结构及形貌进行了表征．结果表明，在650～800℃下后退火1h可获得外延的BiFeO3纳米岛，岛横向尺寸在50～150nm之间，纵向尺寸在6～12nm之间．随着纳米岛后退火温度的升高，其000）面内的几何形貌由三角形状转向四边形状，然后再趋向于长棒状．利用压电力显微镜，对单个BiFeO3纳米岛（横向尺寸～50nm，高度12nm）的铁电特性进行表征．结果表明，单个外延BiFeO3纳米岛内存在分形铁电畴和自偏压极化现象，其中自偏压极化现象来源于外延BiFeO3纳米岛与SrTiO3单晶衬底之间的界面应力．

英文摘要：

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 triangle 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.