SODIUM-DOPED DIMER ROWS ON SI(001)

The stability and electronic structure of a nanowire are studied by fi rst-principles calculations. The wire consists of a single depassivate d silicon dimer row on the hydrogen passivated Si(001) 2x1 surface. We predict that sodium atoms evaporated onto this surface stick preferen tially at the depassivated row and partially fill the empty one-dimens ional states of this row, This leads to a thin metallic wire of atomic size dimensions. At room temperature the sodium atoms are mobile alon g the depassivated row; they become immobile at temperatures before si milar to 120 K.