Structural characterization of epitaxial multiferroic BiFeO₃ films grown on SrTiO₃ (100) substrates by crystallizing amorphous Bi–Fe–O_x

Abstract

Amorphous Bi–Fe–O_x films prepared on SrTiO₃ (100) substrates using a conventional r.f. magnetron sputtering system were crystallized by post-annealing at 873 K in an atmosphere. Microstructural observations by X-ray diffraction and cross-sectional transmission electron microscopy revealed that the crystallized Bi–Fe–O_x films were well-epitaxially BiFeO₃ fabricated without interfacial layer although as-prepared film was amorphous structure with excess Bi. The crystallized BiFeO₃ films have fairly epitaxial compatibly ([001](001)BiFeO₃ // [001](001)SrTiO₃). These results indicate that (1) BiFeO₃ has good epitaxial compatibility with SrTiO₃ and (2) crystallizing amorphous Bi–Fe–O_x is one possible method that can be used to fabricate high-quality multiferroic barriers for tunnel junctions.