XPS study of Cu/substrate systems obtained by pulsed laser deposition

Abstract

AbstractIn this paper XPS was used to study the evolution of Cu 2p3/2 peaks with the increase of the metal coverage on different types of substrate: Ni, HOPG (highly orientated pyrolytic graphite) and KBr. The results showed that: (i) the binding energy of the Cu 2p3/2 peak in the system Cu/HOPG decreases with surface coverage, while in the system Cu/Ni it increases; (ii) with the increase of the Cu coverage in all the systems studied a general trend of the Cu 2p3/2 peak is the reduction of FWHM (full width at half maximum), but the degree of the FWHM change depends greatly on the type of the substrate. The results obtained for binding energy change are discussed in relation to the initial and final state contributions. The results indicate that the final state contributes more to the change of the binding energy in the more 3‐dimensional structure Cu/HOPG system, while in the more 2‐dimensional Cu/Ni system the initial state contribution dominates. The FWHM change is analysed in terms of the size distribution of clusters and change of the lifetime of the holes left by the photoelectrons, which is affected by the size of the clusters and the degree of the hybridization between the s and d electrons. Copyright © 2004 John Wiley & Sons, Ltd.