Van der Waals materials such as graphene are layered materials that can be created in single atom thickness. In most cases there is more than one way to stack subsequent layers, often leading to...Show moreVan der Waals materials such as graphene are layered materials that can be created in single atom thickness. In most cases there is more than one way to stack subsequent layers, often leading to domains of different stackings. In this work stacking domains in few layer stacks of graphene and \mos are studied using Low Energy Electron Microscopy. From dark field LEEM measurements on few layer epitaxial graphene on SiC it is concluded that two different types of domains exists: domains created from nucleation during growth and triangular stress domains induced from lattice mismatch with the underlying SiC. A detailed comparison between epitaxial and quasi-freestanding graphene is made. As part of this comparison deintercalation of the latter to reform the former is performed. The hydrogen diffusion out of the material occurring here is studied and linked to defects in the material and aforementioned stacking domains. For MoS2 no domains were analysed within the scope of this project, but a comparison of flatness for different substrates is made and using muLEED measurements a method to determine the number of layers is demonstrated and the two different orientations of the 2H polytype are experimentally identified.Show less
In this thesis we present two distinct interferometric set-ups for displacement measuring interferometry in cryogenic Low Energy Electron Microscopy (LEEM), specifically for use in ESCHER, the LEEM...Show moreIn this thesis we present two distinct interferometric set-ups for displacement measuring interferometry in cryogenic Low Energy Electron Microscopy (LEEM), specifically for use in ESCHER, the LEEM at Leiden University. The set-ups are based on: 1. circular polarization and 2. 3x3 fiber couplers to obtain a quadrature measurement. Whilst the 3x3 coupler based set-up is limited by thermal drift and other environmental effects, the circular polarization based method displays a 3\sigma resolution of 1.75 nm, and we provide a framework for further increasing this resolution, including a set of alternate set-ups with slight added complexity but a great potential gain in resolution. Keywords: Displacement, Interferometry, Fiber Couplers, Polarization, LEEM, cryogenic, DMI, Quadrature, Fiber.Show less
