Physical Review B 86, 035318 (2012)

The high stability of the Si(100) surface and the possibility of manipulating and functionalising its properties at the atomic level are opening up new perspectives for a wide range of applications. These range from transistor downscaling, dictated by Moore’s law, to quantum computing. The adsorption of single atoms and small inorganic molecules is a key enabling tool for controlling the passivation, oxidation and epitaxial growth of the surface.

We investigate the charging state of an isolated single dangling bond formed on an unpassivated Si(100) surface with c(4×2) reconstruction, by comparing scanning tunneling microscopy and spectroscopy analysis with density functional theory calculations. The dangling bond is created by placing a single hydrogen atom on the bare surface with the tip of a scanning tunneling microscope. We find that the two configurations corresponding to p- and n-doped samples have different scattering properties and phase shift fingerprints. This might open up interesting perspectives for fabricating a switching device by tuning the doping level or by locally charging the single dangling bond state.