Electronic properties of Li and K on graphene: top, hollow and bridge configurations

In this work, I present an analytical Tight Binding Model (TBM), for graphene with adsorbate atoms of lithium and potassium, in different positions of adsorption. The configurations analyzed here are: a) Top site (adsorbate atom on top of the carbon atom of the sublattice A of graphene), b) Hollow site (adsorbate atom in the center of the graphene hexagons), and c) Bridge site (adsorbate atom in the middle of the A-B bridge of the graphene carbon atoms). An ab-initio Density Functional Theory (DFT) is also implemented, in order to contrast the results obtained analytically by TBM. This computational model is useful to obtain the needed parameters for building a precise band structure of graphene according to the adsorption site. The objective of this study is to understand how the electronic structure and electronic properties of graphene are modified when Li and K atoms are in proximity. Additionally, we analyse which are the hybridization of atomic orbitals responsible for the modifications. Our results showed that in the Top (T) and Bridge (B) cases, we encounter that the hybridization between the pz orbital of graphene and the s and p orbitals of the adatom modify the graphene Fermi velocity, downshifts its Fermi level, and the creation of an energy gap between the bands. For the Hollow (H) case, there is a maintenance of the linear dispersion between the energy bands, and there is just a shifting of the Fermi level.

• Hlavní autor: Hidalgo Parra, Andrés Alexander (author)
• Médium: bachelorThesis
• Jazyk: eng
• Vydáno: 2020
• Témata: Grafeno; Efectos de proximindad; Teoría funcional de la densidad; Estructura electrónica; Graphene; Proximity effects; Density-functional theory; Electronic structure; Tight binding; Alkali metal
• On-line přístup: http://repositorio.yachaytech.edu.ec/handle/123456789/296