Effect of chopping on the properties of bismuth oxide thin films

Nanocrystalline bismuth oxide thin films have been deposited by thermal oxidation, in air, of vacuum evaporated chopped bismuth thin films. The optical properties and adhesion have been studied. The oxidation temperature and duration were varied. As revealed by structural investigations, polycrystalline and multiphase bismuth oxide thin films were obtained. At all oxidation temperatures, monoclinic Bi2O3 is predominant. The films showed high transmittance in the visible range of spectrum. The direct band gap of the films obtained was between 2.78 eV and 3.04 eV. The refractive index observed is in the range 1.934 to 2.096. The adhesion of films was in the range 215 × 102 to 470 × 102 kgF/cm2. The values are strongly influenced by the heat treatment characteristics. It was observed that chopping helps in improving the adhesion and increasing refractive index, packing density and band gap of bismuth oxide thin films. These bismuth oxide films can have potential use in optical waveguides.