Formation of nanowires of Bi atoms on a Si(100) surface

We report results of a scanning-tunneling-microscopy investigation of the self-assembly of bismuth nanowires on Si(100) surfaces. Bismuth atoms, adsorbed on the surface at 500°C, form long linear belts (nanowires) on the Si terraces. The nanowires stretch parallel to the × 2 direction of the terrace of the clean Si(100) (2 × 1) surface. The structure of the nanowire is almost perfect, consisting of two chains of bismuth-dimers, which substitute for four Si-dimers per Si-dimer rows in the terrace. When nanowires grow to reach step edges, peninsulas or inlets are formed perpendicular across the step. This may be induced by enhanced migration of atoms along the nanowires. Some defects can be introduced in the nanowires by exposing the surface with nanowires to atomic hydrogen. Such decomposition is attributed to the breaking of Si-Bi bonds by the attack of atomic hydrogen.