Temperature dependence of the optical band gap of sol-gel derived Fe-doped ZnO films

This work presents the characterizations of sol-gel derived undoped nanostructured ZnO and Iron (Fe) doped ZnO films that were deposited onto borofloat glass substrates. To investigate of the effects of Fe doping on the crystallinity and morphological properties, X-ray diffractometer (XRD) and scanning electron microscopy (SEM) were used. The crystallinity of ZnO thin films begins to deteriorate with Fe incorporation and the crystallite size decreased depending on the Fe content. The presence of Fe element in the film was confirmed by EDX analysis. The absorption spectra of the undoped and 5%Fe doped ZnO films were recorded at different temperatures varying from 100 to 300 K to determine the effect of temperature on the optical band gap. Increase in the temperature caused a decrease in the optical band gap and this decrease was investigated by the Varshni, Cody and Bose Einstein relation's formulas and fitting parameters were determined.