Surface structures and electronic states of silicon nanotubes stabilized by oxygen atoms

The geometric and electronic structures of silicon nanotubes stabilized by incorporating oxygen atoms were studied using first-principles calculations within density functional theory. The predicted tubes present one-dimensional characters stacked with n-side silicon polygons connected by oxygen atoms. The stable configurations considered in this work include the tubes with varied facet number of the silicon polygons (n) from n=4 to 28 and of different surface structures. The configurations with n=5, 12, 15, 18, and 21 were found energetically extremely favorable. All the tubes are narrow-band-gap semiconductors with the band gap varying between 0.17 and 0.84 eV, dependent on the surface structure of the tubes. This study provides an interesting route to stabilize silicon nanotubes and tune their electronic properties. (c) 2007 American Institute of Physics.