Atom-resolved three-dimensional mapping of boron dopants in Si(100) by scanning tunneling microscopy

The lack of surface states within the band gap of the perfect Si(100)2×1:H surface opens the way to scanning tunneling microscopy studies of dopant atom sites in Si(100). In this letter, boron-induced features on the Si(100)2×1:H surface are studied by ultrahigh vacuum scanning tunneling microscopy. Filled state images show hillock features while empty state images show local depressions associated with dopants. Furthermore, the amplitudes of these hillock features naturally group such that at least three subsurface layers can be identified. Current image tunneling spectroscopy is performed to study the electronic structure of the boron-induced features, which are explained by a simple model based on tip-induced band bending. This technique for producing atom-resolved three-dimensional maps of electrically active dopants in silicon may be a useful metric for characterizing dopant profiles in ultrasmall electronic device structures.