Propriedades eletrônicas em nanoestruturas de mono e bicamada de grafeno calculadas via modelo tight binding.

• Ano de defesa: 2018
• Autor(a) principal: Bandeira, Nathanaell Sousa
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Grafeno; Nanofitas; Anéis quânticos; Deformação de cisalhamento simples; Potenciais externos
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/49064

In this work, we investigate the electronic properties of confined systems, subject to mechanical perturbation and external potentials in a mono and bilayer graphene using the tight-binding model. Two types of nanostructures were investigated: mono and bilayer nanoribbon of graphene with armchair and zigzag edges, and quantum rings bilayer graphene with different geometric shapes and edges. For monolayer graphene nanoribbons, we induced a simple shear in the structure, with or without constant electric field in the plane, thereby investigating the effects on the energy spectrum. The additive effect of these pertubation opens a gap in the band struture, making the armchair semiconductor ribbon in large thickness scales. In this way we analyze how external parameters such as simple shear strain (γ) and electric field (F), modulate the gap of energy. For bilayer graphene nanoribbon, we analyze the dispersion relation for structures subjected to simple shear strain, with equal intensities in both layers plus electric field perpendicular to the plane of the layers. We verified that the effective action of the simple shear strain modifies the energy levels in a qualitative way to that observed in monolayer graphene nanoribbons, and associating this perturbation with the effect of the electric field perpendicular to the plane, we observed that Bernal stacked in nanoribbon (AB) also exhibit the possibility of modulating the magnitude of the energy gap, making non-gap configurations (ie metal ribbon) into semiconductors. In addition to the work on nanostructures, we developed a systematic study for Bernal-type stacking quantum rings bilayer graphene, investigating the energy and probability density spectra for rings with different types of geometry, edges, inner edge alignment and external, in the presence or absence of magnetic field perpendicular to the structure. Thus, we compare the theoretical results obtained with those reported in the literature for quantum rings in monolayer graphene , highlighting the similarities and differences between the characteristics of such confinement structures.