Design of a very thin direct-band-gap semiconductor nanotube of germanium with metal encapsulation

Abhishek Kumar Singh, Vijay Kumar, Yoshiyuki Kawazoe

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17 Citations (Scopus)


Using ab initio total energy calculations we design a very thin semiconducting nanotube of germanium with a direct band gap by encapsulation of Mo or W. This finding is an outcome of studies of assemblies of Ge 18Nb 2 clusters into nanotubes. The infinite Nb-doped nanotube is metallic. However, the electronic structure has a significant gap above the Fermi level. When Nb is replaced by a Z+1 element such as Mo or W, it leads to the formation of a semiconducting nanotube. The atomic structure of these nanotubes is based on a novel alternate prism and antiprism stacking of hexagonal rings of germanium. Such an arrangement is optimal for Ge 18M 2 (M=Nb, Mo, and W) clusters that serve as the building blocks of nanotubes. These results demonstrate that by just changing the M atom in the growth process, we can form metallic, semiconducting, and n or p types of nanotubes, opening new possibilities for nanoscale devices.

Original languageEnglish
Article number075312
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number7
Publication statusPublished - 2005 Feb 1

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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