DYNAMIC TRANSFORMATION IN THE MORPHOLOGY OF PD-DEPOSITED SI(111) WITHTHERMAL-TREATMENT USING UHV STM

From the dynamic transformation in the morphology of Pd-deposited Si(1 11) surfaces with thermal treatment, observed by ultrahigh vacuum scan ning tunneling microscopy (UHV-STM), the surface reactions of Pd on th e Si(111) surface were clarified for the first time with appropriate m odels on a sound basis. At a low coverage below one monolayer (ML), 2D islands composed of Pd2Si single crystals were clearly observed to be formed via a surface thermal reaction. At high coverages (>2 ML), fol lowing the growth of the epitaxial Pd2Si film a (3 root 3 x 3 root 3)R 30 degrees superstructure appeared over the Pd2Si surface at 300 degre es C. This specific structure was demonstrated to be due to Si segrega tion. (C) 1997 Elsevier Science B.V.