Anisotropic two-dimensional metallic state ofGe(001)c(8×2)-Ausurfaces: An angle-resolved photoelectron spectroscopy

Abstract

The electronic structure of the Ge͑001͒c͑8 ϫ 2͒-Au surface has been investigated by means of angle-resolved photoelectron spectroscopy. The atomic structure of the surface includes nanowires along the ͗110͘ direction separated by deep grooves, which were observed by scanning tunneling microscopy. The dispersion relation along the ͗110͘ direction showed the existence of a metallic surface-state band in accordance with 8ϫ periodicity. Moreover, the Fermi-surface measurement revealed that the band has an ellipsoidal shape, indicating an anisotropic two-dimensional metallic state. This is in contrast to the previously reported one-dimensional character of the system ͓J. Schäfer, C. Blumenstein, S. Meyer, M. Wisniewski, and R. Claessen, Phys. Rev. Lett. 101, 236802 ͑2008͔͒. A structural model including periodic arrangement of Au adsorbed ͑111͒ nanofacets was examined by comparing the electronic structure with that of the flat Ge͑111͒ ͱ 3 ϫ ͱ 3-Au surface.

Properties of 1D metal-induced structures on semiconductor surfaces

“…However, the LDOS curves are comparable. Nakatsuji et al have investigated the electronic properties of the Au/Ge(001) system angle-resolved photoelectron spectroscopy [30]. The experimental findings in this paper regarding the structural and electronic properties of the Au/Ge(001) system are in good agreement with our observations.…”

“…Despite the fact that Pt and Au are adjacent in the periodic table, the Pt/Ge(001) and Au/Ge(001) systems differ significantly. The Pt chains have a height and width of only one atom, whereas the Au-induced chains are several atomic layers in height [24,30,36,37] and the top ridges have a width of two atoms [21,24]. Despite these structural dissimilarities, there is another interesting difference: the Pt nanowires are static at room temperature, whereas the Au-induced nanowires are, at least partly, dynamic.…”

“…The deposition of Au and Pt on Ge(001) substrates leads, after proper treatment, to incredibly well-ordered arrays of nanowires that are perfectly straight and have lengths of up to micrometers [13,20,21,23,24,30,[33][34][35][36][37]. Despite the fact that Pt and Au are adjacent in the periodic table, the Pt/Ge(001) and Au/Ge(001) systems differ significantly.…”

“…One important class of these nanostructures is formed by nanowires. During the last decade, several types of self-organized nanowires have been reported, such as Au on stepped Si(111), Pt on Ge (001) and Au on Ge(001) [13,20,21,23,24,[30][31][32][33][34][35]. However, before such nanowires can be applied in nanodevices, it is of the utmost importance to have a detailed understanding of their structural and electronic properties.…”

Modeling 1D structures on semiconductor surfaces: synergy of theory and experiment

“…28,29,97,[166][167][168][169] To resolve this point, a series of ARPES experiments have been published since 2009, which show the nature of this band to be a complicated issue, in which experimental limitations often preclude a definite and final answer. 100,104,170,171 The experiments show that there exists a highly anisotropic electronic band near the Fermilevel, which may well be 1D. The presence of a secondorder phase transition at 585 K, which appears to be of a 3D Ising type, indicates the NWs to be influenced by the substrate.…”