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Journal of Nanomaterials
Volume 2008, Article ID 874213, 18 pages
Review Article

Toward a Detailed Understanding of Si(111)- Surface and Adsorbed Ge Nanostructures: Fabrications, Structures, and Calculations

Nanoscale Physics & Devices Laboratory, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080, China

Received 30 August 2007; Accepted 11 January 2008

Academic Editor: Jun Lou

Copyright © 2008 Ye-Liang Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Firstly, both the rest atoms and the adatoms of Si(111)- surface are observed simultaneously by scanning tunneling microscopy (STM) when the sample bias voltages are kept less than − 0.7 V. The visibility of the rest atoms is rationalized by first-principle calculations and a very sharper tip can resolve them. Secondly, the behaviors of various Ge nanostructures fabricated on Si(111)- , ranging from the initial adsorption sites of individual Ge atoms to the aggregation patterns of Ge nanoclusters, and then to 2D extended Ge islands, are comprehensively investigated by STM. The individual Ge atoms tend to substitute for Si adatoms at Si(111)- with the preference of corner adatoms in the faulted half unit when keeping substrate at C. With increasing Ge coverage, individual Ge atoms and Ge nanoclusters coexist on the substrate. Subsequently, the density of Ge nanoclusters increase and cluster-distribution becomes gradually regular with the formation of final 2D extended hexagonal configuration. When keeping the substrate at C, Ge islands consisting of more complicated reconstructions with intermixing Ge/Si components are present on the substrate. The detail structural characterizations and the bonding nature of the observed Ge nanostructures are enunciated by the first-principle calculations.