Non-classical effects of extrinsic doping on Au quantum wires

Self-assembled atomic wires on vicinal Si(hhk) surfaces are very versatile quasi-1D objects to study their interaction with the embedding environment [1,2]. Here we employ plasmon spectroscopy to study the response of Au-induced quantum wires to extrinsic doping by hydrogen adsorption. Si(553) and Si(557) surfaces are used as templates, which form double and single atomic strands per terrace upon evaporation of 0.48ML and 0.19ML of Au, respectively.
The present study shows that the plasmonic excitation on both surfaces is strongly modified upon hydrogenation of the Si environment. These modifications are specific to the structural Au motif on the surface. Although hydrogen adsorption never happens on the Au chains directly, it clearly modifies the band structure of the whole system including the Au chains. The effects range from simple charge donation and changes of band filling, as for Si(553)-Au, to opening of band gaps partly even close to the Fermi energy as for Si(557)-Au, that will be discussed in detail.

1. T. Lichtenstein, Z. Mamiyev, C. Braun, S. Sanna, W. G. Schmidt, C. Tegenkamp, and H. Pfnür, Phys. Rev. B 97, 165421 (2018)
2. Z. Mamiyev, T. Lichtenstein, C. Tegenkamp, C. Braun, W. G. Schmidt, S. Sanna, and H. Pfnür, Phys. Rev. Materials 2, 066002 (2018)