Effect of thickness on optical properties of nickel vertical posts deposited by GLAD technique

Abstract

Nickel (Ni) thin films of different thicknesses (25 nm to 150 nm) were deposited on glass substrates using Glancing Angle Deposition technique. Characterization of obtained Ni films was performed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry and by four-point probe method. Variations in optical parameters with thickness correlated with structural, chemical and electrical properties of nanostructured nickel thin films were studied. The results showed that deposit is porous and consists of nano-scaled columns, which grow perpendicular to the substrate. It was found that the size of the columns and the surface roughness change with film thickness. Spectroscopic ellipsometry revealed that the refractive index and extinction coefficient varied with thickness, which can be correlated with changes in microstructure of Ni films. Additionally, the relationship between the film microstructure and its resistivity was also analyzed. It was found that the variations in Ni films resistivity could be attributed to the changes in the width of the columns. The increasing of layer thickness leads to overall decrease of optical resistivity of nickel thin films.