Effect of Fe3+ doping on structural, optical and electrical properties δ-Bi2O3 thin films

Fe3+ doped δ-Bi2O3 thin films were prepared by sol-gel method on quartz glass substrate at room temperature and annealed at 800 °C. The thin films were then characterized for structural, surface morphological, optical and electrical properties by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption measurements and d.c. two-probe, respectively. The XRD analyses revealed the formation δ-Bi2O3 followed by a mixture of Bi25FeO40 and Bi2Fe4O9. SEM images showed reduction in grain sizes after doping and the optical studies showed a direct band gap which reduced from 2.39 eV for pure δ-Bi2O3 to 1.9 eV for 10% Fe3+ doped δ-Bi2O3 thin film. The electrical conductivity measurement showed the films are semiconductors.