STM STUDIES OF SUBMONOLAYER COVERAGES OF AG ON GE(111)

Submonolayer coverages of Ag on Ge(111) have been studied under ultra- high vacuum using STM. Atomically resolved images of the (root 33 x ro ot 33)R30 degrees reconstruction have been obtained. The images obtain ed from the 4 x4 structure are strongly dependent upon the bias voltag e polarity, indicating a significant influence from electronic effects . A new model is proposed which has the reconstruction occurring withi n the top bi-layer of an unreconstructed Ge(111) surface. STM images o f the (root 33 x root 33)R30 degrees reconstruction show a structure v ery similar to that obtained for Ag/Si(111), indicating that the surfa ce is a honeycomb-chained-trimer structure. Images have also been obta ined of 3 x 1 and 5 x 1 regions and possible models for these structur es are proposed. (C) 1998 Elsevier Science B.V.