ADATOM PAIRING STRUCTURES FOR GE ON SI(100) - THE INITIAL-STAGE OF ISLAND FORMATION

With the use of scanning tunneling microscopy, it is shown that german ium atoms adsorbed on the (100) surface of silicon near room temperatu re form chainlike structures that are tilted from the substrate dimer bond direction and that consist of two-atom units arranged in adjoinin g substrate troughs, These units are distinctly different from surface dimers. They may provide the link missing in our understanding of the elementary processes in epitaxial film growth: the step between monom er adsorption and the initial formation of two-dimensional growth isla nds.