Comparative analysis of fractal dimension of CdS, CdZnS and CdZnS:Ce thin films

CdS, CdZnS, and CdZnS:Ce thin films are prepared by using the chemical bath deposition (CBD) technique. Thin films were prepared on glass substrates. A 3D view of Atomic Force Microscope images of prepared samples is shown, which indicates that the thickness of prepared samples is in the nanometer range. Fractal dimensional analysis is very useful in the characterization of thin films. In this paper, characterization of CdS, CdZnS, and CdZnS:Ce thin films has been done by fractal dimensional analysis and roughness analysis of Atomic Force Microscope images. The fractal dimension of prepared samples has been calculated by three different methods: Box Counting, power spectrum, and the triangulation method. It was found that fractal dimension can be increased by mixing Zn and Ce in the base material CdS. which shows the more complex structure of CdZnS and CdZnS:Ce than the base material CdS. This is a comparative study of the fractal dimension and roughness of Atomic Force Microscope images by different fractal dimension analysis methods. The roughness value of AFM images of prepared samples has been calculated and found to increase, which shows that particles present on the surface decrease in size. Surface Skewness (Ssk) and Surface Kurtosis (Sku) are another two parameters calculated from different AFM images. A positive Surface Skewness (Ssk) value indicates the presence of a number of peaks on the surface of AFM images. A Surface kurtosis (Sku) value is equal to or greater than 3.0 and indicates a sharper height distribution. A 2D Fast Fourier Transformation image provides information about the surface topography. The peaks in the fourier transform image show the periodicity of AFM images. The flat and slope regions in the PSD graph indicate that the surface structure is in both the microscale and nanoscale range.