Metal-semiconductor behavior of metallic carbon nanotubes adsorbed on hydrogenated Si(001) surfaces
Abstract
We report first-principles total-energy calculations of a metallic (6,6) carbon nanotube (CNT) adsorbed on a fully hydrogenated Si surface [H/Si(001)] as well as on partially hydrogenated Si surfaces [H_0.75/Si(001) and H_0.50/Si(001)]. For the CNT on H_0.75/Si(001) and H_0.50/Si(001), the number of H atoms at the CNT-surface interface are half the value and zero, respectively, that those found at the CNT-H/Si(001) interface. We find a weak (van der Waals like) interaction between the CNT and H/Si(001), where the CNT has a binding energy of 0.08 eV/Å\. The band structure calculations show that the CNT preserves almost unchanged its metallic character when adsorbed on H/Si(001). For the CNT on H_0.75/Si(001), we find that half the Si atoms at the CNT-surface interface (the depassivated one) form chemical bond with C atoms of the CNT. We observe an increase on the density of states at the Fermi level along the tube axis, as compared with the CNT on H/Si(001), induced by the formation of the C-Si bonds. Finally, for the CNT on H_0.50/Si(001), we find that all the Si atoms at the CNT-surface interface bind with C atoms of the CNT. The band structure along the tube axis shows a semiconducting character for the CNT when adsorbed on H_0.50/Si(001). These results suggest that the conductance of a metallic CNT adsorbed on H/Si(001) may be controlled by removing H atoms at specific regions of the CNT-H/Si(001) interface without changing the CNT structure.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARN16014O