Thesis (Ph.D.), Memorial University of Newfoundland, 1999. / Bibliography: p. 97-104.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 64-70). Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 132-135).

Thesis (M.S.)--Rochester Institute of Technology, 2006. / Typescript. Includes bibliographical references (leaves 171-181).

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 221-230).

Thesis (M.S.)--Texas State University-San Marcos, 2007. / Vita. Appendices: leaves 69-80. Includes bibliographical references (leaves 81-83).

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abstract: Silicon solar cells with heterojunction carrier collectors based on a-Si/c-Si heterojunction (SHJ) have a potential to overcome the limitations of the conventional diffused junction solar cells and become the next industry standard manufacturing technology of solar cells. A brand feature of SHJ technology is ultrapassivated surfaces with already demonstrated 750 mV open circuit voltages (Voc) and 24.7% efficiency on large area solar cell. Despite very good results achieved in research and development, large volume manufacturing of high efficiency SHJ cells remains a fundamental challenge. The main objectives of this work were to develop a SHJ solar cell fabrication flow using industry compatible tools and processes in a pilot production environment, study the interactions between the used fabrication steps, identify the minimum set of optimization parameters and characterization techniques needed to achieve 20% baseline efficiency, and analyze the losses of power in fabricated SHJ cells by numerical and analytical modeling. This manuscript presents a detailed description of a SHJ solar cell fabrication flow developed at ASU Solar Power Laboratory (SPL) which allows large area solar cells with >750 mV Voc. SHJ cells on 135 um thick 153 cm2 area wafers with 19.5% efficiency were fabricated. Passivation quality of (i)a-Si:H film, bulk conductivity of doped a-Si films, bulk conductivity of ITO, transmission of ITO and the thickness of all films were identified as the minimum set of optimization parameters necessary to set up a baseline high efficiency SHJ fabrication flow. The preparation of randomly textured wafers to minimize the concentration of surface impurities and to avoid epitaxial growth of a-Si films was found to be a key challenge in achieving a repeatable and uniform passivation. This work resolved this issue by using a multi-step cleaning process based on sequential oxidation in nitric/acetic acids, Piranha and RCA-b solutions. The developed process allowed state of the art surface passivation with perfect repeatability and negligible reflectance losses. Two additional studies demonstrated 750 mV local Voc on 50 micron thick SHJ solar cell and < 1 cm/s effective surface recombination velocity on n-type wafers passivated by a-Si/SiO2/SiNx stack. / Dissertation/Thesis / Ph.D. Electrical Engineering 2013

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Abstract The main objective of this thesis is to study unique cases for computer-assisted finite element modeling (FEM) of thermal, mechanical and thermo-mechanical problems related to silicon and carbon. Computational modeling contributed to solve scientific problems either by validating the experimental results obtained earlier or by predicting the behavior of a particular system. In the model generation phase, emphasis is placed on simplification of a physical problem without loosing the validity or important details. As a consequence of reasonably reduced variables and also degrees of freedom of the elements in our models, the simulations could be performed using a commercial FEM software package, ANSYS®. To test the capabilities of the method (i) a steady-state finite element thermal analysis has been accomplished and verified by experiments for the case of laser-assisted heating of different materials. (ii) Mechanisms (Dember and Seebeck effects) responsible for the reduction of gold ions and deposition of metallic gold on p-type semiconductors from liquid precursors have been investigated by computing the surface temperature profiles of silicon wafers exposed to laser irradiation. (iii) Temperature field in a multi-component system caused by laser illumination was modeled to determine the heat affected zone in the case of laser soldering of flip-chips on transparent printed circuit board assemblies. (iv) Origin of the experimentally observed residual strain in thermally oxidized porous silicon structures was revealed by computing the strain fields in silicon-silicon oxide porous materials considering both intrinsic and thermal stress components. (v) Finally, we demonstrated that Joule heat generated on a silicon chip can be removed efficiently using micro-fin structures made from aligned carbon nanotubes. Computational fluid dynamics and thermal-electric finite element models were developed to study the steady-state laminar coolant flow and also the temperature distribution for the chips. The presented novel results have potential in silicon and carbon nanotube based technologies, including deeper understanding of the processes and problems in manufacturing electronic devices.