Metallic Transport in a Monatomic Layer of In on a Silicon Surface

Department of Physics, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Physical Review Letters (Impact Factor: 7.51). 03/2011; 106(11):116802. DOI: 10.1103/PhysRevLett.106.116802
Source: PubMed


We have succeeded in detecting metallic transport in a monatomic layer of In on an Si(111) surface, Si(111)-sqrt[7]×sqrt[3]-In surface reconstruction, using the micro-four-point probe method. The In layer exhibited conductivity higher than the minimum metallic conductivity (the Ioffe-Regel criterion) and kept the metallic temperature dependence of resistivity down to 10 K. This is the first example of a monatomic layer, with the exception of graphene, showing metallic transport without carrier localization at cryogenic temperatures. By introducing defects on this surface, a metal-insulator transition occurred due to Anderson localization, showing hopping conduction.

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Available from: Yukio Hasegawa
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    • ". However, despite the fact that the phase diagram for positive temperatures in Celsius scale and coverages up to 1 ML was presented as early as in 1979 [4], the system is constantly being studied and it seems that some observations still remain unclear. Of particular interest are atomic models for those structures [5] [6] [7] [8] and the nature of In-covered Si surfaces [9] [10]. One of the very interesting phases which was widely studied in 1990s [3] [11] is the √ 7 × √ 3 structure. "
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    • ")-In surface was prepared by thermal evaporation of In onto a clean Si(111) substrate, followed by annealing at around 300°C for approximately 10 s in UHV [18-20], and was subsequently confirmed by low-energy electron diffraction and STM. The sample was then patterned by Ar + sputtering through a shadow mask to define the current path for four-terminal resistance measurements. "
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