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Published July 7, 2013 | Published
Journal Article Open

Optoelectronic analysis of multijunction wire array solar cells


Wire arrays have demonstrated promising photovoltaic performance as single junction solar cells and are well suited to defect mitigation in heteroepitaxy. These attributes can combine in tandem wire array solar cells, potentially leading to high efficiencies. Here, we demonstrate initial growths of GaAs on Si_(0.9)Ge_(0.1) structures and investigate III-V on Si_(1-x)Ge_x device design with an analytical model and optoelectronic simulations. We consider Si_(0.1)Ge_(0.9) wires coated with a GaAs_(0.9)P_(0.1) shell in three different geometries: conformal, hemispherical, and spherical. The analytical model indicates that efficiencies approaching 34% are achievable with high quality materials. Full field electromagnetic simulations serve to elucidate the optical loss mechanisms and demonstrate light guiding into the wire core. Simulated current-voltage curves under solar illumination reveal the impact of a varying GaAs_(0.9)P_(0.1) minority carrier lifetime. Finally, defective regions at the hetero-interface are shown to have a negligible effect on device performance if highly doped so as to serve as a back surface field. Overall, the growths and the model demonstrate the feasibility of the proposed geometries and can be used to guide tandem wire array solar cell designs.

Additional Information

© 2013 AIP Publishing LLC. Received 25 April 2013; accepted 10 June 2013; published online 2 July 2013. We are grateful to Emily Warmann for assistance in detailed balance calculations, to Dr. Mike Kelzenberg and Dr. Mike Deceglie for their aid with Sentaurus, to Dr. Nick Strandwitz for helpful discussion, and to all of our teachers and family for their help and support through the years. Support for this work was provided by the United States Department of Energy under Grant No. DE-EE0005311. D.B.T-E. acknowledges the NSF for fellowship support.

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Published - JApplPhys_114_014501.pdf


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