16.8%-Efficient n+/p GaAs Solar Cells on Si with High Short-Circuit Current Density

Shizhao Fan, Daehwan Jung, Yukun Sun, Brian D. Li, Diego Martin-Martin, Minjoo L. Lee

Research output: Contribution to journalArticle

Abstract

The highest efficiency heteroepitaxial GaAs solar cells on Si have historically been grown in the p+/n polarity, which was preferred due to the decreased sensitivity of open-circuit voltage in such cells to threading dislocations. The n+/p polarity also has potential advantages due to the higher mobility of electrons than holes in GaAs, and most multi-junction solar cells in the literature are grown in this polarity. Here, we demonstrate n+/p GaAs solar cells on Si with a certified AM1.5G efficiency of 16.8%, approaching the best certified efficiency of 18.1% for p+/n cells in the literature. The high efficiency of our n+/p cells is primarily due to the short-circuit current density of 26.5 mA/cm2, which is significantly higher than prior p+/n record cells. The strong carrier collection results from the use of a highly transparent AlInP window layer, thin n+ emitter, and a relatively high minority electron diffusion length in the p-type base. The high quantum efficiency of these n+/p cells at wavelengths of 700-880 nm makes them promising for future triple-junction devices on Si, where the GaAs will serve as a middle sub-cell.

Original languageEnglish (US)
Article number8638510
Pages (from-to)660-665
Number of pages6
JournalIEEE Journal of Photovoltaics
Volume9
Issue number3
DOIs
StatePublished - May 2019

Keywords

  • GaAs on Si
  • III-V on silicon
  • molecular beam epitaxy (MBE)
  • n+/p cells

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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