Structural and electronic effects of adatoms on metallic atomic chains in Si(111)5 × 2-Au

Abstract

We investigate the effects of native Si adatoms on structural and electronic properties of the Si(111)5 × 2-Au surface, a representative one-dimensional metal-chain system, by means of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. High-resolution STM images of relatively long adatom-free chain segments evidence directly the inherent ×2 reconstruction, which is the essential part of a recently proposed structural model based on a renewed Au coverage of 0.7 monolayer. On the other hand, STM images for chain segments of different lengths reveal that the structural distortion induced by Si adatoms is confined in neighboring unit cells, in good agreement with DFT calculations based on that model. Si adatoms greatly affect the metallic bands of Au chains, one of which becomes fully occupied and represents a tightly confined electronic state to the distortion around Si adatoms, potentially forming short insulating segments within metallic chains. This finding provides an atomic-scale understanding of the observed gradual metal-insulator transition and atomic-scale phase separation induced by Si adatoms.

Indirect mechanism of Au adatom diffusion on the Si(100) surface

“…Moreover, the presence of a gold overlayer on silicon has proven to play an important role in the growth mechanism of silicon oxide [8] and other materials [9]. Stripes of Au on silicon surfaces have also been studied extensively in recent years, for example, the electronic structure and surface dynamics of Au wires on flat [10] and stepped [11,12] silicon surfaces.…”

Unveiling the hybridization between the Cr-impurity-mediated flat band and the Rashba-split state of the α-Au/Si(111) surface

“…Among a number of heavy elements, gold has one of the largest atomic SOC values and is a quite promising candidate for synthesizing low-dimensional materials owing to its exotic electronic phenomena. For example, the Au/Si(111)-5 × 2 system arranged in a quasi-1D manner 23–26 demonstrates a number of fascinating phenomena such as adatom-related metal–insulator transition, 27–29 spin-polarised metallic states, 30 1D domain-wall hoppings, 31 and atomic-scale Schottky barriers. 32 In the two dimensions, the Au overlayer displays a number of reconstructions, among which the most vivid example is the α-Au/Si(111)- surface known to exhibit a large Rashba-type spin splitting of metallic surface-state bands, 33 if being stabilized by appropriate adatom impurities.…”