Enhancement of Light Matter Interaction of Thin Film Materials in Optoelectronic Devices: Plasmonic Antennas, Electro-Optic Modulators, and Solar Cells
Open AccessThe most often cited challenge in the field of nanoscale optoelectronics is the weak light matter interaction that has traditionally led to bulky optoelectronic components in scales comparable to the wavelength of light (~500 nm). Recently ultra-thin film (0.5-20 nm) materials have demonstrated to have unique potential for applications in planar optoelectronic and integrated photonics. However, the small optical path across such ultra-thin film materials is the major limiting factor in their optoelectronic performance. In this dissertation, I discuss my PhD research activities in enhancement of light matter interaction of ultra-thin film materials in optical resonant cavities for photo-emission, photo-absorption, and electro-optic modulation application by localizing optical energy in Plasmonic, Fabry-Perot, and Micro-Ring cavities.Transition metal dichalcogenides (TMDs) are stable and naturally occurring semiconductors of two-dimensional (2D) materials that offer well-defined tunable direct band gaps when thinned down to a nanometer. To increase the visible light emission from direct bandgap of TMD monolayers for application in LEDs, nanoscale plasmonic antennae offer a substantial increase of the electric field strength over very short distances, comparable to the native thickness of the TMD. Here I report on the emission enhancement generated in TMD films by several nanoantenna geometries compared to their intrinsic emission. Next, to increase the photo-absorption of TMD thin films further, to compete with thick classical materials, I propose and investigate a novel stack of 2D material heterostructure forming a core-shell light-concentrating optical cavity. This structure is motivated by deploying the mechanical flexibility of 2D materials to enable a multilayer solar cell without the necessity to contact each of the layers separately. We further investigate and demonstrate a spectral filtering metasurface for selective guiding of solar spectrum for smart power windows. Finally, Indium tin oxide, that is already an industrial transparent conducting oxide material, shows strong electro-optic tunability in their thin films (~10 nm). I study its application in a novel micro ring reservoir coupling as a wavelength scale CMOS compatible phase modulator on silicon photonic platform.In conclusion, novel nano-photonic components have been proposed and demonstrated to outperform traditional optoelectronics by taking advantage of the unique properties of atomically thin film materials and optical cavities. These finding are important for fast growing application of photonics in lighting, telecommunication, and optical energy conversion.
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Tahersima_gwu_0075A_14188.pdf | 2018-06-10 | Open Access |
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