Optical Study of Sol-gel Processed Nd-doped BiFeO3 Multiferroic Films by Spectroscopic Ellipsometry

We have prepared undoped and Nd-doped BiFeO3 films on Si(100) by sol-gel method. XRD measurements show that all the films are single perovskite structure and a phase transition appeared in Nd doping BiFeO3 films. Dense microstructure with evenly distributed grains about 100nm is observed by SEM. The ellipsometric measurements were carried out in the UV-visible region and the corresponding experimental data were fitted by using a model consisting of air/roughness/BNFO/Si(100). It has been found that the optical constants tend to increase with Nd content increasing, however, the optical band gap decreases as Nd content increasing.