Polycrystalline thin films of d-Bi2O3 were prepared by oxidising bismuth films of thickness (120-350 nm) in air at 473 K for 10 hours. X-ray diffraction analysis showed that the films are polycrystalline and correspond to cubic dphase of Bi2O3. The electrical and optical properties of d-Bi2O3 were studied. The effect of the film thickness on these properties was also investigated. From the electrical conductivity measurements at various temperatures (100-473 K), the coexistence of band and multiphonon-assisted hopping conduction between well-localized states has been observed. It was found also that the activation energy DE increases and the density of localized states at the Fermi level gr decreases with increasing thickness of the film. The analysis of the absorption coefficient data revealed the existence of an indirect transition. It was found that the calculated value of the optical energy gap Egopt increases with increasing thickness of the film.
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