One-dimensional molecular wire on hydrogenated Si(001)

An important example of hybrid organic-silicon systems is the fabrication of styrene molecular wires on a H-passivated Si(001) surface. Here we theoretically demonstrate that a styrene molecule which easily adsorbs on a single H-empty site can be further stabilized (with an energy barrier of 0.88 eV) by abstracting an,H atom from a neighboring Si dimer. This H-abstraction process creates another H-empty site, setting off a chain reaction that results in the growth of a styrene wire along the Si dimer row. Our simulated scanning tunneling microscope (STM) image for the resulting one-dimensional (1D) molecular wire is in good agreement with STM data. In particular, the antibonding pi orbitals on adjacent styrene molecules overlap, thus providing "channels" that permit charge transport along this 1D wire under a voltage bias.