The influence of Bi content on the properties of bismuth ferrite thin films fabricated by magnetron sputtering

In the process of BiFeO3 film preparation by magnetron sputtering, Bi element is volatile, leading to the films which often appear impurity phases. Therefore, Both Bi excessive 5% (B_1.05FO) and 8% (B_1.08FO) BFO film in Si substrate were prepared by magnetron sputtering. X-Ray Diffraction (XRD) results showed that the BFO thin films fabricated in the Si substrate are perovskite structure, that the B_1.08FO film appeared less impurity phases than B_1.05FO film, and that stress due to substrate lattice mismatch caused the shift of XRD patterns. In Raman study, it was concluded that both B1.08FO film and B_1.05FO film appeared ten Raman peaks in the range from 50cm-1 to 800cm-1, and that B B_1.08FO Raman peaks intensity was stronger in 137.1cm-1.168.5cm-1 and 215.3cm-1. Spectroscopic ellipsometry test showed that the refractive index and the extinction coefficient of B_1.05FO film were 2.25 and 0.07 respectively in 600 nm with 2.67eV of energy gap; the refractive index and the extinction coefficient of B_1.08FO film were 2.14 and 0.05 in 600 nm respectively with 2.71eV of energy gap. Atomic Force Microscope (AFM) was used to characterize the film surface morphology, finding that the B1.08FO film prepared in Si substrate was denser while grain size and surface roughness were smaller.