Investigation of interface properties of Ni Cu multilayers by high kinetic energy photoelectron spectroscopy

High kinetic-energy photoelectron spectroscopy (HIKE) or hard x-ray   photoelectron spectroscopy has been used to investigate the alloying of   Ni/Cu (100) multilayers. Relative intensities of the corelevels and   their chemical shifts derived from binding energy changes are shown to   give precise information on physicochemical properties and quality of   the buried layers. Interface roughening, including kinetic properties   such as the rate of alloying, and temperature effects on the processes   can be analyzed quantitatively. Using HIKE, we have been able to   precisely follow the deterioration of the multilayer structure at the   atomic scale and observe the diffusion of the capping layer into the   multilayer structure which in turn is found to lead to a segregation in   the ternary system. This is of great importance for future research on   multilayered systems of this kind. Our experimental data are   supplemented by first-principles theoretical calculations of the   core-level shifts for a ternary alloy to allow for modeling of the   influence of capping materials on the chemical shifts