Abstract
The action of atomic hydrogen on clean cleaved (1 1 1) surfaces of highly doped silicon samples, both phosphorus ([n] = 2 × 1019 cm-3) and boron ([p] = 4 × 1019 cm-3) doped has been compared to the case of lightly doped samples ([n] = 1 × 1014 cm-3). Once cleaved under ultra high vacuum, the samples were exposed to increasing doses of atomic hydrogen up to saturation. Before and after each hydrogen exposure, the Si(1 1 1) 2 × 1 surface was studied by low energy electron diffraction (LEED) and photoemission yield spectroscopy (PYS). The compared PYS measurements show that H atoms adsorbed on the Si(1 1 1) surface at room temperature do totally compensate the shallow-acceptor impurities (boron) and only partially the shallow-donor impurities (phosphorus) in the space charge region. They also remove the surface dangling bond states. These effects are reversible upon heating under vacuum. Both surface stresses and space charge electric field play a role in this compensation effect.