Effect of angle of deposition on the Fractal properties of ZnO thin film surface

Highlights: • ZnO films are deposited at various angle of deposition. • The Higuchi's algorithm is applied on AFM micrographs to compute Fractal dimension. • Hurst exponent was computed from the fractal dimension. • The fractal dimension (Hurst exponent) affected by the grain size of the deposited films. • The Hurst exponent (fractal dimension) has the same (opposite) nature as the grain size of the film. - Abstract: Zinc oxide (ZnO) thin films were prepared by atom beam sputtering at various deposition angles in the range of 20–75°. The deposited thin films were examined by glancing angle X-ray diffraction and atomic force microscopy (AFM). Scaling law analysis was performed on AFM images to show that the thin film surfaces are self-affine. Fractal dimension of each of the 256 vertical sections along the fast scan direction of a discretized surface, obtained from the AFM height data, was estimated using the Higuchi's algorithm. Hurst exponent was computed from the fractal dimension. The grain sizes, as determined by applying self-correlation function on AFM micrographs, varied with the deposition angle in the same manner as the Hurst exponent.