PROBING ATOMICALLY INHOMOGENEOUS SURFACES WITH TUNNELING MICROSCOPY

The connection between observed, physical properties of adsorbed surfaces and their microscopic origins requires structural determination at the atomic level. Yet, investigation of such systems at that scale reveals local inhomogeneities in both reconstruction and individual atomic species at various stages of adsorbate incorporation. We have studied the submonolayer growth of Ga and B on Si(111) with tunneling microscopy and spectroscopy, and we show for each known phase assumed by these systems that images of mixed-phase surfaces provide structural information for new reconstructions which would not be accessible from images of a homogeneous, single-phase surface. Where mixing of adsorbate and substrate atoms occurs within a surface phase, individual atoms of two species may be identified. We demonstrate that controlled surface doping of Si(111) by boron induces identifiable changes in the local character of specific adatom sites leading to device characteristics associated with the presence of the tunneling tip over particular atoms. © 1990.