Studies of nanostructure fabrication and morphology development during ion bombardment as a function of bombardment angle

Thesis (B.A.)--Boston University. University Professors Program Senior theses.PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.In order to investigate the behavior of nanostructures during the widely-used process of ion bombardment, the mechanisms of ion bombardment on nanostructures were studied. Nanostructures were fabricated into silicon wafers. The fabrication process involved writing with scanning electron microscopy (SEM) a pattern in poly(methyl methacrylate) (PMMA) polymer resist layered over the silicon, removing the written PMMA in development with methyl isobutyl ketone (MIBK) and isopropanol, layering the wafer with chromium in thermal evaporation, removing the PMMA and its chromium covering with acetone, etching the chromium of the pattern with reactive ion etching, and finally removing the chromium with an etching reagent. The final structures were ion bombarded under 3*10^-3 torr for three hours at 1000 V and 40mA, with Argon; the bombarding was performed at degree angles of 60 and normal incidence. A sample without the fabrication of structures is bombarded at normal incidence as well. One sample with fabricated structures is studied without bombardment as an experimental control. The results were erosion of the bombarded structures, cones and dots.2031-01-0

Nanoplasmonics: Enhancement of Optical Radiation

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Efficient solar vapor/steam generation is important for various applications ranging from power generation, cooling, desalination systems to compact and portable devices like drinking water purification and sterilization units. However, conventional solar steam generation techniques usually rely on costly and cumbersome optical concentration systems and have relatively low efficiency due to bulk heating of the entire liquid volume. Recently, by incorporating novel light harvesting receivers, a new class of solar steam generation systems has emerged with high vapor generation efficiency. They are categorized in two research streams: volumetric and floating solar receivers. In this paper, we review the basic principles of these solar receivers, the mechanism involving from light absorption to the vapor generation, and the associated challenges. We also highlight the two routes to produce high temperature steam using optical and thermal concentration. Finally, we propose a scalable approach to efficiently harvest solar energy using a semi-spectrally selective absorber with near-perfect visible light absorption and low thermal emittance. Our proposed approach represents a new development in thermally concentrated solar distillation systems, which is also cost-effective and easy to fabricate for rapid industrial deployment