CHARGE-TRANSFER AND REDISTRIBUTION IN THE FORMATION OF THE K GAP(110)INTERFACE - A PHOTOELECTRON-SPECTROSCOPY STUDY/

We present the results of a photoelectron spectroscopy study of the K/ GaP(110) interface grown at T = 120 K. We have investigated the system looking at the Ga 3d and P 2p core level spectra by analysing their l ineshape. This analysis shows that the transferred charge in the adato m-substrate bonding formation affects the electronic and chemical envi ronment of both surface Ga and P atoms. The results suggest relevant d ifferences with the intuitive picture of strong ionic localized bondin g between the alkali atom and surface Ga. They are instead more consis tent with a delocalized redistributed valence charge between the adsor bate and the substrate. We also conclude that the system at Theta = 1 ML is metallic, with an increasing disorder and inhomogeneity at the h ighest coverage studied. The similarities and differences with the Na/ GaP(110) and the other alkali metal/GaAs(110) systems are discussed.