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Paper   IPM / Nano-Sciences / 8704
School of Nano Science
  Title:   Finite-concentration gas molecule adsorption on carbon nanotubes investigated by a tight binding
1.  Rostam Moradian
2.  Yawar Mohammadi
  Status:   Published
  Journal: Phys. Rev. B
  No.:  15
  Vol.:  76
  Year:  2007
  Pages:   155432
  Publisher(s):   The American Physical Society
  Supported by:  IPM
A theoretical approach based on tight-binding model is developed to study the effects of finite concentrations of adsorption of diatomic gas molecules in the general form denoted by X2 and also triatomic gas molecules in the general form denoted by YX2 on the single-walled carbon nanotube SWCNT electronic properties. To obtain proper hopping integrals and random on-site energies, for the case of one molecule adsorption, the local density of states for various hopping integrals and random on-site energies are calculated. We found, for some specified values of hopping integrals and random on-site energies, adsorbed molecule bound states located inside the 10,0 SWCNT energy gap, where it is consistent with the reported experimental results for O2 and NO2 adsorption, while for other values, there are no bound states inside of energy gap. The last case is similar to the N2 and CO2 adsorption on semiconductor SWCNTs. Then, by using these obtained parameters and coherent potential approximation, we investigate the effects of finite gas molecule adsorption on the average density of states. Our results could be used to make a p-type or n-type semiconductors by finite-concentration adsorption of gas molecules.

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