Influence of Al-doping on microstructure and optical properties of sol-gel derived CdO thin films

In this work, un-doped and Al doped cadmium oxide (CdO) films with different Al concentrations were grown onto ITO (In2O3; Sn) glass substrates using sol-gel dip coating technique. The influence of Al doping on the structural, morphological and optical properties of CdO thin films was systematically studied. XRD analysis showed that the films have poly-crystalline structures with cubic phase having (1 1 1), (2 0 0), (2 2 0) and (3 1 1) orientations. The AFM images were taken to see the effects of Al doping on surface topography and roughness of CdO thin films. From the SEM analysis, it has seen that nanostructured particles have homogeneously distributed and well hold onto the ITO substrate surface. The optical properties were examined by a UV-vis spectrometer, which indicated high optical transparency in the visible region and a decrease of the direct band gap value from 3.03 to 2.77 eV, as the aluminum concentration in solution increases.