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Carrier-selective contact GaP/Si solar cells grown by molecular beam epitaxy

  • Chaomin Zhang (a1), Ehsan Vadiee (a1), Richard R. King (a1) and Christiana B. Honsberg (a1)

Integration of the III–V material systems on Si is an enabling technology for achieving high efficiency heterojunction Si-based photovoltaic devices. Gallium phosphide (GaP) offers numerous potential electrical, optical, and material advantages over amorphous silicon (a-Si) for the realization of several heterojunction solar cell designs. In this paper, details are given for the growth, fabrication, and characterization of different n-GaP/n-Si heterojunction solar cells to explore the effect of GaP as a carrier-selective contact. The cell performance is promising with high Si bulk lifetime (∼2.2 ms at the injection level of 1015 cm−3) and an open-circuit voltage of 618 mV and an efficiency of 13.1% in this new solar cell design. In addition to GaP as an electron-selective contact, MoO x was successfully implemented as a hole-selective contact in the n-GaP/n-Si heterojunction solar cell, increasing efficiency to 14.1% by improving the short wavelength response. The Si bulk lifetime is maintained during growth of GaP on Si by two different approaches and their effects on GaP/Si solar cell performance are also presented.

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Journal of Materials Research
  • ISSN: 0884-2914
  • EISSN: 2044-5326
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