Group IV elements in 2D structures

Abstract

Starting from the discovery of graphene, the two-dimensional (2D) materials field has received a massive increase in interests over the recent 15 years. Due to major obstacles in utilizing graphene for electronics, the attention of the scientific community turned to other elemental 2D materials, in particular from group IV of the periodic table. This thesis is a contribution to the 2D materials field, with a particular focus on group IV elemental 2D materials. By utilizing several complementary surface science experimental techniques, we investigated the formation of ordered structures in 2D regime and interactions between these materials and various substrates. Scanning Tunneling Microscopy (STM) and Low Energy Electron Diffraction (LEED) provided information about structural ordering, while Scanning Tunneling Spectroscopy (STS), and (Angle Resolved) Photoelectron Spectroscopy ((AR)PES) gave insight into chemical composition and electronic structure of the obtained system. In chapter 2, we review and systematize the experimental aspects of the knowledge about substrates suitable for epitaxial growth of stanene. Chapter 3 is a pioneer approach to combine two 2D materials in one system by growing epitaxial Sn on silicene terminated ZrB2. Out investigation showed that Sn grows on the substrate in various forms, in particular a mosaic-like alloy and an ordered monolayer. Chapter 4 shows our investigation on epitaxial growth of Sn on MoS2. The deposited Sn formed disordered, liquid-like droplets on the surface, which, upon annealing, etched the surface of the substrate. Deposition at lowered temperature resulted in ordered islands of Sn, which are assigned to be composed of the β-Sn allotrope. Finally, in Chapter 5 we investigate the dependence of Li intercalation between multilayer graphene sheets on the defect density in the graphene. Counterintuitively, the number of defects did not influence the intercalation capacity. The reason for this was attributed to step edges taking the primary role in the diffusion of Li in between graphene sheets, as well as a clogging mechanism, where Li atoms accumulate on the defects, effectively screening them from other atoms.