Interface formation of Ag and Au with InP 001/2=4: a photoemission study

Interface formation and growth of silver on an IBA prepared indium-phosphide- 001.2=4 surface was studied by photoelectron spectroscopy at room temperature and at 110 K. Sequences of angle resolved core-level and valence-band spectra of substrate and ad-metal were recorded in the 0.05–10 ML coverage regime. Analysis of the change of shape of spectra rendered information on ad-layer growth mode and composition. Results for AgrInP from this study are compared to those of a corresponding study on AurInP, performed under identical conditions as presented in a previous paper: both metals are found to behave in the same way at low temperature, forming a closed layer on the substrate with minute admixture of indium. At room temperature, however, silver shows island growth from the beginning while gold is growing in islands on an intermixed layer. There is substrate disrupture and indium admixture in both cases; gold turns out to be the more reactive metal; a model calculation of reaction enthalpies is in line with this result. q1999 Elsevier Science B.V. All rights reserved