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Doping effects on metallic and semiconductor single-wall carbon nanotubes

TitleDoping effects on metallic and semiconductor single-wall carbon nanotubes
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2007
AuthorsBuonocore, F.
JournalPhilosophical Magazine
Volume87
Pagination1097-1105
ISSN14786435
KeywordsBoron, Carbon nanotubes, Conduction bands, Crystal impurities, Energy gap, Impurity band, Isomers, Nitrogen, Probability density function, Semiconductor doping, Semiconductor materials, Single-wall carbon nanotubes
Abstract

In this paper we investigate nitrogen- and boron-doped zigzag and armchair single-wall carbon nanotubes (SWNTs) with theoretical models based on the density functional theory. We take into account nitrogen and boron doping for two isomers in which substitutive atoms are on opposite sides of the tube, but only in one isomer the impurity sites are symmetrical with respect to the diameter. The band structures show a strong hybridization with impurity orbitals that change the original band structure. Although the two isomers of armchair SWNT exhibit the same formation energy, their band structures are different. Indeed asymmetrical isomers are gapless and exhibit a crossing of valence and conduction bands at k=/c, leading to metallic SWNTs. Band structures of symmetrical isomers, on the other hand, exhibit an energy gap of 0.4eV between completely filled valence and empty conduction bands. We use density of charge in order to understand this difference. In zigzag SWNT an impurity band is introduced in the energy gap and for N doping this band is just partially occupied in such a way that the electronic behaviour is reversed from semiconductor to metallic. Whereas for a given isomer armchair SWNT shows similar behaviours of N- and B-doped structures, B-doped zigzag SWNTs present different band structure and occupation compared to the N-doped case.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-33847106850&doi=10.1080%2f14786430601032352&partnerID=40&md5=0f52dd70583e8b2ed94c86122fe8ae70
DOI10.1080/14786430601032352
Citation KeyBuonocore20071097