Multifractal spectra of atomic force microscope images of Cu/Fe nanoparticles based films thickness

Abstract This paper analyses the thickness influence of Fe on Cu nanoparticles (NPs) synthesised by Direct-current (DC) magnetron sputtering on the three-dimensional (3-D) surface morphology of thin films. The thin films with Cu nanoparticles were deposited on glass substrates then; Fe nanoparticles were added to Cu ones. These nanostructures were investigated at one deposition thickness of Cu and three of Fe (Cu 55 nm, Cu 55 nm/Fe 40 nm, Cu 55 nm/Fe 55 nm, and Cu 55 nm/Fe 70 nm as thin films’ thickness), by means of X-ray diffraction, atomic force microscopy (AFM) and multifractal analysis, in order to evaluate the structure and relation among the 3-D micro-textured surface. The 3-D morphology of surface samples exhibits multifractal features characterized by nano-irregularities of various orders of size and different local densities spread on the surface. The local and global scale properties of 3-D surface geometry were quantitatively estimated using the generalized dimension Dq and the singularity spectrum f(α). The non-uniformity of the nano-irregularities are correlated with the generalized dimension Dq and the spectrum width Δα (Δα = αmax − αmin) of the multifractal spectra f(α). Multifractal approach in correlation with the surface statistical parameters are a sensitive and reliable tool for quantifying the thickness influence of Fe on Cu nanoparticles (NPs) synthesised by Direct-current (DC) magnetron sputtering on the 3D surface morphology of thin films.