Two-dimensional materials: electronic and structural properties of defective graphene and boron nitride from first principles

• Ano de defesa: 2014
• Autor(a) principal: Lídia Carvalho Gomes
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Física
• Link de acesso: http://hdl.handle.net/1843/BUOS-9PQGRK

We use first principles calculations based on the formalism of Density Functional Theory (DFT) to investigate electronic and structural properties of graphene and boron nitride two-dimensional materials. In the first work, we present a study of stability and electronic properties of nine different models for extended one-dimensional (1D) defects in monolayer BN. A low-energy stoichiometric model for an armchair-direction antiphase boundary (APB) in monolayer BN is introduced. The second work investigates four different grain boundaries in bilayer graphene, aiming an understanding of the degree of localization of the electronic states in the atoms that compose the line defects. Interesting results like magnetic instabilities and changes from metallic to semi-metallic character of these systems are discussed. In the third work we study the low-energy electronic transport across stacking boundaries in graphene. The electron scattering by interfaces formed between regions of monolayer and bilayer graphene is investigated by a continuum approach. The fourth work was developed in collaboration with the experimental group of the National University of Singapore (NUS) which synthesized coherent interfaces between graphene and h-BN. We use DFT calculations to investigate the introduction of a core dislocation in the h-BN lattice as a mechanism of strain release in order to keep the continuity of the film along the interface. In the fifth work we present a recently started study of two-dimensional semiconductors monochalcogenides, focus on the electronic and optical properties of these materials.