Abstract: This dissertation presents a quantitative study of the physical mechanisms underlying the anomolously large recombination current experimentally observed in heavily doped regions of silicon pn-junction solar cells and bipolar transistors. The study includes a comparison of theoretical predictions with a variety of experimental observations in heavily doped silicon and silicon devices. A major conclusion is that the simplest physical model that adequately describes the heavily doped regions must include Fermi- Dirac statistics, a phenomenological excess intrinsic carrier density (or deficit impurity concentration), Auger recombination in the bulk, and recombination at the surface. These mechanisms are incorporated in a first-order model useful in the design of silicon pn-junction solar cells. The accuracy of the first-order model is supported by comparing its results with the results of more detailed models and of a numerical analysis of the problem. Experimental data are presented that are consistent with the predictions of the first-order model and of the numerical solution. Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Device Physics for Engineering Design of Heavily Doped Regions in Pn-junction Silicon Solar Cells" by Muhammed Ayman Shibib, was obtained from University of Florida and is being sold with permission from the author. A digital copy of this work may also be found in the university's institutional repository, IR@UF. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation.