Engineering Light-Matter Interactions in Graphene and Transition Metal Dichalcogenides

Abstract

This thesis describes studies concerning light-matter interactions in graphene and tungsten diselenide in two separate research projects united in theme and application. The research performed for the first project studies the tunability of the nonlinear response in plasmonic graphene disks in the presence of an applied magnetic field. The research performed for the second project studies how electron-beam irradiation affects the excitonic populations in tungsten diselenide, a transition metal dichalcogenide, and whether encapsulation in hexagonal boron nitride is capable of mitigating these effects. For both projects, the properties of the two-dimensional materials were confirmed through Raman spectroscopy and atomic force microscopy, and microelectronic fabrication processes were performed based on electron-beam lithography patterning, with the first project also involving additional processing like plasma etching, metal evaporative deposition, and metal lift-off patterning. For the first project, measurement techniques including transmission spectroscopy, terahertz time-domain spectroscopy, and terahertz pump-probe spectroscopy were used to determine how various factors including radiation wavelength, magnetic field, material properties, material interactions, and plasmonic resonance structure design affect the light-matter interactions within these engineered graphene disks. For the second project, low-temperature photoluminescence measurements were performed to ascertain the effects of electron-beam irradiation on the excitonic populations in tungsten diselenide with and without a hexagonal boron nitride encapsulation.