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.
University of Minnesota. M.S. thesis. December 2011. Major: Civil Engineering. Advisor: Paul Ruden,. 1 computer file (PDF); vii, 124 pages, appendices A-D.
Krohn, Jennifer Jo.
Exploration of graded indium gallium nitride heterojunction solar cells for laterally integrated, spectrally-split solar cell arrays..
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