SurfaceScience21 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 33: Poster Session III: Semiconductor substrates I
O 33.6: Poster
Dienstag, 2. März 2021, 10:30–12:30, P
Enhancing structural order by random Au adsorption on the Si(553)-Au system — •Christa Fink1, Kris Holtgrewe1, Simone Sanna1, Zamin Mamiyev2, and Herbert Pfnür2 — 1Justus-Liebig-Universität, Gießen, Germany — 2Leibniz Universität, Hannover, Germany
Nanowires on semiconductor surfaces have drawn the attention from a broad research community as they are promising systems for realizing and studying quasi 1D physics. We investigate the adsorption of additional Au adatoms on the Au double chain system supported by the silicon (553) surface by means of density functional theory and slab models. One adatom per (5×2) unit cell strongly enhances the Au chain dimerization, although the favored adsorption site is at the Si step edge far away from the chains. This non-local structure manipulation is related to the two-dimensional coupling between the wire and the substrate. The electronic band structure proves that the hybridization between the Au adatom and the Si step edge transfers charge to the surface. Because of the strong electronic correlation, a band gap opens within the Au related states which is accompanied by an increased dimerization of the Au chains. The Au adsorption has a similar impact on the surface morphology as a pure electron injection. As the enhanced dimerization puts a penalty on the formation energy of defects, the not necessarily ordered adsorption of Au adatoms reduces the number of defects and leads to more order in the wires. This counter-intuitive order-by-disorder mechanism is confirmed by experimental results and transferable to other quasi 1D nanowire systems.