Estudo teórico de impurezas em nanoestruturas

• Autor(a) principal: Lopes, Mirleide Dantas
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/tede/7995
• topic: h-BN; Bilayers; Grafeno; Bicamadas; Bicones e estrutura eletrônica; Bicones; h-BN and graphene; CIENCIAS EXATAS E DA TERRA::FISICA

Investigating the stability and electronic structure of nanomaterials is essential for their application in electronic devices. In this thesis were analysed two types of nanostructures, a derivative of h-BN and the other of graphene. This analysis was performed using first-principles calculations by Density Functional Theory (DFT), implemented by the SIESTA code. First we investigated two kinds of stacks of h-BN bilayer with impurities and by means of the calculation of interaction and formation energies was identified the most stable bilayers, both due to the nature of the stack and to the type impurity introduced. We also note that the combination of these two effects cause considerable variations in the gaps of energy and impurity. We also use an electric field perpendicular to the plane of the bilayer and observe different changes in the electronic structure related to the permanent electric dipole moment of each nanostructure. The second nanomaterial investigated in this work, the Carbon bicones have been proposed based on the experimental observation of nanocones. The possibility of bicones are experimentally obtained was analyzed by comparing the stability of these nanostructures with existing cones. It was found that some of them are as stable as the cones, which, at least theoretically, enables the synthesis of these nanomaterials. The effect of the electric field and impurities on the electronic structure of bicones were also analyzed, resulting in significant changes in the state density, evidenced by the emergence of new states near the Fermi level