Navegando por Assunto "Nanotubos de nitreto de boro"

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Acesso aberto (Open Access)
Analysis of electronic structure of boron nitride nanotubes with different positions of intrinsic impurities
(2014-12) GOMES, Fernando Antonio Pinheiro; DMITRIEV, Victor Alexandrovich; NASCIMENTO, Clerisson Monte do
The pristine boron nitride nanotubes have a large direct band gap around 5 eV. This band gap can be engineered by doping. We investigate electronic structure of the doped hexagonal boron nitride (5,5) nanotubes using the linearized augmented cylindrical wave method. In particular, this work focuses on systematical study of the band gap and the density of states around the Fermi-level when the nanotubes are doped by intrinsic impurities of two substitutional boron atoms in a super cell and a comparative analysis of the relative stability of three structures studied here. This corresponds to 3.3% of impurity concentration. We calculate 29 configurations of the nanotubes with different positions of the intrinsic impurities in the nanotube. The band gap and density of states around the Fermi level show strong dependence on the relative positions of the impurity atoms. The two defect sub bands called D∏(B) appear in the band gap of the pristine nanotube. The doped nanotubes possess p-type semiconductor properties with the band gap of 1.3-1.9 eV.
Acesso aberto (Open Access)
Um estudo sobre a influência de defeitos de diferente natureza nas propriedades eletrônicas de nanotubos usando o método das ondas cilindricas linearizadas aumentadas
(Universidade Federal do Pará, 2014-12-12) GOMES, Fernando Antonio Pinheiro; PELAES, Evaldo Gonçalves; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/0684541646225359
The carbon and boron nitride nanotubes are one-dimensional structures which exhibit behavior both as metallic and semiconductor, depending on their chirality, except for the nanotubes of boron nitride which always have semiconductor characteristics, for pristine nanotubes. Due to their electronic characteristics, the nanotubes have great potential for application in nanoelectronic devices, such as nanodiodes, nanotransistors, interconnection elements, etc. For this reason, it is important to understand how external factors influence on the properties of such materials. One such factor is the introduction of external defects in the nanotubes. Such defects are the absence of one or more carbon atoms belonging to carbon nanotube and nitrogen or boron for boron nitride nanotubes, or the substitution of carbon, nitrogen or boron atoms by different ones in the structure of the corresponding nanotubes. This work presents a theoretical study of the effects of the introduction of a substitutional defects in the electronic properties of carbon and boron nitride nanotubes, via ab-initio simulation. The energy band and density of states structures was evaluated for both semiconducting and metallic carbon nanotube armchair and zig-zag types respectively and for boron nitride nanotube only armchair type using the method LACW - linearized augmented cylindrical waves. Furthermore, due to the boron nitride nanotubes are growing in importance, we make an additional systematic study of the electronic structure for these nanotubes, for a super cell formed by three unit cells, using intrinsic doping as well as quantitative analysis about relative stability based on the total energy and band gap value of these structures.