Exploring van der Waals Materials: From Nanofabrication to Strain Mapping using Transmission Electron Microscopy

The quest to miniaturize optical and electronic devices has driven significant interest in transition metal dichalcogenides (TMDs) like molybdenum disulfide (MoS₂) due to their remarkable optoelectronic properties. This thesis explores the synthesis, structural control, and advanced characterization of MoS₂, with a focus on vertically-aligned nanosheets for enhanced non-linear optical applications. A novel 4D-STEM framework, StrainMAPPER, is developed to map strain at atomic resolution, revealing critical insights into bandgap modulation. Additionally, convergent beam electron diffraction (CBED) techniques are used to identify crystal domains and grain boundaries. These findings contribute to advancing the fabrication and characterization of TMD nanomaterials, enabling new platforms for tunable nanoelectronics and nanophotonics.