The Si(111) $\sqrt 3 \times \sqrt 3 $ SURFACES FORMED BY THE ADSORPTION OF GROUP-III, IV, AND V METALS

Abstract

A compilation of experimental studies is made on the properties of the Si(111) surfaces formed by the adsorption of metals of groups-III, IV, and V in the periodic table. The metals treated are Al, Ga, In (group-III), Sn, Pb (group-IV), Sb and Bi (group-V). Experimental studies using scanning tunneling microscopy are included only when they are necessary, since the topics will be covered in the review by J. Nogami in this issue. Theoretical aspects of the studies will be covered in the review by H. Nagayoshi in this issue. The geometric and electronic properties of these Si(111) surfaces appeared to be the simplest kinds of surfaces on the Si(111), thus providing prototypic examples of reconstruction on the metal/Si submonolayer interfaces. The simplicity in these surfaces is that there are metal-adatoms over essentially truncated Si(111) 1×1 substrates. The types of "metal building-blocks" are basically two: (i) a single metal adatom on a threefold hollow site (so-called T₄ site), (ii) a metal trimer, each of constituent atoms, resides nearly on the ontop site (so-called "milk-stool"). There is large relaxation in the substrate Si due to the presence of metal adatoms.