Krohn, Jennifer Jo2012-01-312012-01-312011-12https://hdl.handle.net/11299/120091University of Minnesota. M.S. thesis. December 2011. Major: Civil Engineering. Advisor: Paul Ruden,. 1 computer file (PDF); vii, 124 pages, appendices A-D.The ternary group III/group V direct bandgap semiconductor alloy system of indium gallium nitride is emerging as a material with great potential for the production of highly efficient, low cost terrestrial photovoltaic devices. Indium gallium nitride alloy is a direct bandgap semiconductor with an energy gap in the range of 0.7 eV to 3.4 eV depending on the alloy composition. Here we explore a unique photovoltaic device design based on indium gallium nitride single-junction pin graded heterojunction cells arranged laterally and illuminated by a spectrally-split solar spectrum. Mathematical models for photon absorption, charge carrier generation, total charge carrier concentrations, and charge carrier flow are derived and suitable software tools are developed, implementing these equations as well as power density and efficiency calculations to simulate the photovoltaic device operation under maximum power point conditions. Efficiencies of the individual cells in the array differ significantly with the largest bandgap pin producing the highest fill factor and energy conversion efficiency. The small bandgap n-doped layer contributes the largest amount of photogenerated electron-hole pairs, and increasing the width of this layer leads to significantly larger efficiencies. Overall, the photovoltaic device yields efficiencies competitive with existing technologies. Modifications to the design can be incorporated into the software to explore additional methods of increasing efficiencies.en-USElectrical engineeringThesis or Dissertation