Ultra-large scale transition metal dichalcogenides: fabrication and exploitation

Two-dimensional materials have emerged as a versatile platform for exploring novel physical phenomena and enabling innovative device architectures. Among them, transition metal dichalcogenides (TMDCs), such as molybdenum disulfide, are of particular interest due to their unique optical and electronic properties, including a thickness-dependent bandgap, strong excitonic effects, and spin-valley coupling. These characteristics make TMDCs promising candidates for next-generation electronic, optoelectronic, and photonic technologies. Realizing the full potential of TMDCs requires reliable fabrication methods. This thesis presents the development of two gold-assisted exfoliation techniques designed to produce high-quality monolayer flakes. The first method utilizes APTES-functionalized target substrates to enhance flake adhesion. The second introduces a mechanically constraining layer that enables direct exfoliation onto arbitrary substrates without the need for surface functionalization. A comprehensive characterization confirms the high structural and optical quality of the exfoliated flakes. Imaging spectroscopic ellipsometry is demonstrated as an effective technique for assessing TMDC thickness over large areas. Additionally, the phenomenon of laser-induced photoluminescence enhancement in molybdenum disulfide monolayers is investigated and attributed to local healing of sulfur vacancies. Finally, the robustness of the exfoliated monolayers is validated through their integration into nanofabrication workflows. Specifically, thermal scanning probe lithography (t-SPL) is employed to create metallic nanostructures directly on top of monolayer molybdenum disulfide without degrading its optical properties. These results highlight the versatility of gold-assisted exfoliation for 2D material exploitation in advanced devices.