Transition metal dichalcogenides (TMDs) represent a steadily growing class of layered, two-dimensional (2D) van der Waals materials, exhibiting a broad variety of electronic, optical and mechanical properties, thus rising tremendous research interest for device applications. Due to their layered, highly surface dependent nature the properties of 2D materials strongly depend on their environment. On the one hand, this offers a wide variety of platforms for on-surface chemical modification and functionalization to target specific material properties. On the other hand, the exposed surface is highly susceptible to contamination, such as environmentally adsorbed hydrocarbons or polymers introduced during processing steps, such as material storage, packaging, shipping or structuring. Therefore, full control over the material surface is crucial and can only be achieved by exhaustive surface analysis. Amongst material characterization techniques, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy are widely applied for the investigation of 2D materials. However, these techniques have instrumental and physical drawbacks which limit the material data they can provide. For example, only Raman active vibrations can be detected due to selection rules and the lateral resolution is limited by the diffraction of light. XPS offers elemental analysis and can even determine binding states of the atoms but the detection is limited to concentration levels of ~1%. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) complements these conventional analytical techniques, offering superior concentration detection limits down to ppm levels for inorganic and organic materials. TOF-SIMS can achieve a lateral resolution of ~100 nm and, especially important for monolayered, thin materials, a depth resolution of 1 nm during depth profiling. In this thesis, entitled “Investigation of Two-Dimensional Transition Metal Dichalcogenides with Time-of-Flight Secondary Ion Mass Spectrometry” I want to present and advance the application of TOF-SIMS in 2D material investigation. So far, the application of TOF-SIMS in 2D material analysis remains scarce but I showcase analytical studies, where this technique helps to identify the true chemistry of pristine and functionalized 2D material surfaces on the nanoscale, as well as buried interfaces of the layered materials and their substrates.    «

Transition metal dichalcogenides (TMDs) represent a steadily growing class of layered, two-dimensional (2D) van der Waals materials, exhibiting a broad variety of electronic, optical and mechanical properties, thus rising tremendous research interest for device applications. Due to their layered, highly surface dependent nature the properties of 2D materials strongly depend on their environment. On the one hand, this offers a wide variety of platforms for on-surface chemical modification and fun...    »