Effect of annealing temperature on optical properties of undoped and antimony doped tin oxidethin films.

In this work we studied an effect of annealing temperature on the optical properties for pure SnO2 and (Sb: 1% and 3%) doped (SnO2). Thin films have been prepared by the method of chemical spray pyrolysis for (SnCl4.5H2O) with molar concentration (0.1mol). The XRD technique test showed that these films show polycrystalline structure. The study showed that the transmittance before annealing increases as the Sb doped SnO2 increasing and for Sb: 1% the transmittance reaches 85% as maximum and after annealing the transmittance for pure SnO2 increases by effect annealed temperature to reach 92% as maximum. The optical parameters as absorption, extinction and refractive index coefficient before and after annealing have been calculated .The absorption coefficient value suggests the allowed and forbidden direct transition are dominant .The energy forbidden gap of allowed direct transition increases as the doped percentage increasing and values allowed direct transition befor and after annealing were (3.6, 3.8, 3.75) eV and (3.8, 3.96, 3.82) eV for pure SnO2, 1% and 3% respectively. Values of forbidden direct transition are calculated too.