Effect of Heat Treatment Under Nitrogen Atmosphere on Sprayed Fluorine Doped In2O3 Thin Films

Fluorine-doped indium oxide thin films (In2O3:F) were prepared at 500A degrees C for different fluorine concentrations (0 at.%, 2 at.%, 6 at.% and 10 at.%) using the chemical spray pyrolysis technique. Structure and surface morphology of these films were characterized by x-ray diffraction (XRD) and atomic force microscopy (AFM). XRD analysis revealed that fluorine doped In2O3 thin films exhibit a centered cubic structure with the (400) preferential orientation. The change of the preferential reflection plane from (222) to (400) was found after doping. The doping optimum concentration of thin film crystal structure is obtained witha fluorine ratio equal to 2 at.%. The crystallinity improvement of In2O3:F (2 at.%) film is detected after annealing at 200A degrees C, 300A degrees C, and 400A degrees C in nitrogen gas for 45 min. Transmission and reflection spectra measurements were performed over the wavelength range of 250-2500 nm. The band gap energy increase from 3.10 eV to 3.45 eV was detected after treatment at 400A degrees C. In parallel, the electrical resistivity, deduced from Hall effect measurements, decreases from 428.90 x 10(-4) Omega cm to 6.58 x 10(-4) Omega cm.