Investigation of the Optical Properties in Low-Dimensional Materials and Heterostructures




Joshi, Jaydeep

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The introduction of layered two-dimensional (2D) materials that offer unconventional pathways to harness and engineer many-body quantum effects has provided new possibilities to develop next-gen optoelectronic and computational applications. In the last decade, the rediscovery of a new class of 2D materials called the transition metal dichalcogenides (TMDs) have proved to be key candidates for advanced technology needs, made possible through materials synthesis, growth, and ease of exfoliation. Additionally, TMDs can be easily integrated in stacks, also called heterostructures, tailoring them for emergent phenomena at interfaces between materials with varying structural and electronic properties. Particularly fascinating is their innate polymorphic nature, which offers energetically-inexpensive alternatives to achieve phase-transitions in materials that exhibit multiple crystallographic and electronic characteristics. In this dissertation, we employ fundamental spectroscopy techniques to investigate intriguing properties and quantum phenomena in 2D TMDs. This involves studying atypical materials that exhibit novel structural and electronic phase transitions, understanding the role of defects in the optical properties of synthetically grown materials, and proximity effects coupled to interfaces shared between two materials with distinct band-structure, work functions, and electron-correlated physics. These results elucidate the importance of quantum correlations in complex low-dimensional materials and heterostructures and highlight some of the challenges that continue to be barriers for the 2D community.



Condensed matter physics, Materials Science, Optics, Charge density waves, Phase transitions, Photoluminescence, Proximity effects, Transition metal dichalcogenides, VdW heterostructures