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Published June 2018 | public
Book Section - Chapter

GaP/Si Heterojunction Solar Cells: An Interface, Doping and Morphology Study


We report on an study of the GaP/Si interface for application in silicon heterojunction solar cells. We analyzed the band alignment using X-ray photoelectron spectroscopy (XPS) and cross-sectional Kelvin probe force microscopy (x-KPFM). Our measurements show a high conduction band offset (0.9 eV) leading to a barrier in electron extraction which we microscopically resolved via x-KPFM. XPS reveals the presence of Si-Ga bonds which explains the observed interface dipole that leads to low open circuit voltage and low fill factor in GaP/Si heterojunction solar cells. Furthermore, we investigated the electronic and morphologic changes in GaP upon Si and Mg doping.

Additional Information

© 2018 IEEE. The authors acknowledge the Molecular Foundry for generously hosting the MOCVD growth and the Caltech MMRC for providing the XPS analytic tools. We thank Laura Ding, Shaul Aloni, Adam Nielander, Noah Plymale, Amanda Shing and Lars Korte for helpful advice with measurements and data interpretation. The information, data, or work presented herein was funded in part by the U.S. Department of Energy, Energy Efficiency and Renewable Energy Program, under Award Number DE-EE0006335 for band offset characterization and EEC1041895 for other electrical and structural measurements. 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.

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August 19, 2023
October 19, 2023