Effects of Bismuth Oxide Buffer Layer on BiFeO 3 Thin Film

Bismuth ferrite (BiFeO 3 ) thin films with Bi 2 O 3 buffer layers were prepared on Si/SiO 2 /TiO 2 /Pt substrates by sol–gel‐derived spin‐coating method. The structural and electrical properties of BiFeO 3 was effectively improved by adding a Bi 2 O 3 buffer layers either at Pt/BiFeO 3 interface or on BiFeO 3 surface, also strongly depending on the positions and the annealing conditions of buffer layers. A 500°C‐annealed Bi 2 O 3 buffer layer could act as a Bi source for compensating Bi volatilization and a diffusion barrier for species from BiFeO 3 . A near stoichiometric BiFeO 3 with less defects and substrate contamination was obtained by employing a 500°C‐annealed Bi 2 O 3 buffer layer in between Pt substrate and BiFeO 3 . The structure change in BiFeO 3 led by such a buffer layer should result from the interfacial constraint between buffer layer and BiFeO 3 . Furthermore, this crystalline BiFeO 3 specimen exhibited a highly (100)‐textured, where this preferred orientation was attributed to the accumulation of Bi at Pt/ BFO interface. Therefore, the Pt/500°C‐annealed Bi 2 O 3 /BiFeO 3 /Pt thin film exhibited the good ferroelectric and magnetic properties. As compared to the usual method for controlling BiFeO 3 composition by adding excess Bi, this study indicates the more advantages using a Bi 2 O 3 buffer layer.