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Published June 2013 | public
Book Section - Chapter

Design and growth of III-V on Si microwire array tandem solar cells


Tandem Ga_(1-x)In_xP/Si microwire array solar cells are a route towards a high efficiency, low cost, flexible, wafer-free solar technology. Coupled full-field optical and device physics simulations of a Ga_(0.51)In_(0.49)P/Si wire array tandem are used to predict device performance. A 500 nm thick, highly doped "buffer" layer between the bottom cell and tunnel junction is assumed to harbor a high density of lattice mismatch and heteroepitaxial defects. Under simulated AM1.5G illumination, the device structure explored in this work has a simulated efficiency of 23.84% with realistic top cell SRH lifetimes and surface recombination velocities. The relative insensitivity to surface recombination is likely due to optical generation further away from the free surfaces and interfaces of the device structure. To move towards realizing these device structures, GaP and Ga_(1-x)In_xP layers were grown heteroepitaxially with metalorganic chemical vapor deposition on Si microwire array substrates. The layer morphology and crystalline quality have been studied with scanning electron microscopy and transmission electron microscopy, and they provide a baseline for the growth and characterization of a full device stack.

Additional Information

© 2013 IEEE. Special thanks go to Emily Warmann and Dr. Virginia Altoe for assistance in detailed balance calculations and TEM. Financial support for this work was provided by the EERE SunShot Initiative, Next Gen PV II award number DOE DEEE0005311. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect those of NSF or DOE. D.B.T-E. acknowledges the NSF for fellowship support.

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