AN AES STUDY OF THE SI-GD INTERFACE ELECTRONIC-STRUCTURE

An AES study of the cleaved Si surface with deposited Gd has been carr ied out in situ using Si L1L2,3 V, L2,3 VV, KLL and GdN4,5 Auger spect ra and Si L2,3 VV plasmon loss. The results indicate a decreasing Si 3 p electron density on the Si atom, and growth of Si effective positive charge, for a coverage of 0.2 ML Gd. Further deposition of 1.3 ML Gd leads to the growth of Si effective negative charge, growth of Gd effe ctive positive charge, formation of Si-Gd bonds and a decrease in elec tron concentration in the surface layer. A possible model of Si-Si bon d weakening before these bonds break and Si-Gd bond formation is discu ssed.