Effect of Deposition Temperature on the Formation of Defect Phases in BiFeO3 Thin Films

Abstract

We report the effects of deposition temperature on the evolution of defect and second phases and on the ferroelectric properties of BiFeO3 thin films. We grew BiFeO3 thin films on (001) SrTiO3 substrates by using pulsed laser deposition at temperatures in the range of 570 − 600 ◦ C at intervals of 10 ◦ C. We found that defects and a resulting second phase appeared at temperatures greater than 590 ◦ C. The second phase led to significant changes in the optical absorption and to the appearance of impurity peaks in the X-ray diffraction data. An analysis of the X-ray diffraction data indicated that the second phase was Fe2O3. Atomic force microscopy measurements showed that the appearance of defects accompanied an abrupt increase in the surface roughness. Furthermore, the presence of the second phase significantly affected the ferroelectric hysteresis. Our results suggest that the evolution of defects and resulting second phase in BiFeO3 thin films depends strongly on the deposition temperature.