Growth mode of ultrathin gold films deposited on nickel

Gold ultrathin overlayers were evaporated on polycrystalline nickel within 17 deposition steps. Mean thicknesses of the deposit in the range from 0.07 to 3.8 nm were determined by a quartz microbalance. Growth mode and morphology were examined using three different methods. First two methods are based on analysis of X-ray induced photoelectron spectra (XPS), the last one on the elastic peak electron spectroscopy (EPES). The Au 4d XPS lines with extended part of background intensity were analysed using the QUASES-Tougaard software. The XPS ratio method, commonly used for uniform overlayers thickness estimation, was applied to the Au 4f and Ni 3p peak areas. The EPES method is based on measurements and Monte Carlo (MC) calculations of elastic electron backscattering probability in the low kinetic energy range (200–1000 eV), where the method has a high surface sensitivity. The results obtained show that an initial growth mode of the gold overlayer is not uniform and indicate formation of gold 3D islands on nickel.