The growth mode of Cu overlayers on Pd(100)

The growth mode of Cu deposits on clean Pd(100) has been studied by means of LEED. AES and angular resolved ultraviolet photoemission spectroscopy. Auger signal versus deposition time curves showed that the growth follows a layer-by-layer mode for two monolayers after which it involves formation of islands as in the Stranski-Krastanov model. Despite the large lattice mismatch between Cu and Pd (7.7%) the substrate p(1×1) LEED pattern persisted with clear distinct spots at least up to the equivalent coverage of 4 ML indicating that Cu starts to grow epitaxially with the Pd lattice constant (pseudomorphic growth). Photoemission results show that the spectrum of the Cu/Pd(100) system does not converge to that of bulk Cu(100) until about 65 ML equivalent coverage. The spectrum below that coverage is composed of separate contributions from the thick regions and from the pseudomorphic basic slab.