Surface characterization of Cu-doped indium sulfide thin films

In the present work, Cu-doped indium sulfide thin films (In₂S₃:Cu) have been produced by chemical bath deposition (CBD) method on the glass substrates. The deposited films have been post-annealed at 300 °C temperature for about one hour. The morphological properties of produced thin films have been investigated analytically before and after the Cu doping process. To this end, the atomic force microscopy analysis has been used to study the height fluctuations of these rough thin films. By the monofractal analysis, the height distribution, and the higher-order moments (skewness and kurtosis) of the surface height have been studied. The deviation from the Gaussian distribution has been shown by the results. Also, the correlation function and therefore the correlation length of the produced surfaces have been investigated. The numerical calculations revealed that the morphology and the statistical properties of thin films depend on the growth method. The power spectral density has been evaluated, and the achieved results of higher-order moments of the surface height have been confirmed. The skewness values of thin films heights are nonzero; moreover, the obtained kurtosis values illustrate the mild peak respect to Gaussian distribution. The Hurst exponent and thus the fractal dimensions of surfaces have been estimated. (author)