Optical properties of Al<inf>x</inf>Ga<inf>1-x</inf>As/GaAs superlattice solar cells

Makoto Kuramoto, Hiroyuki Urabe, Tomohiro Nakano, Atsushi Kawaharazuka, Jiro Nishinaga, Toshiki Makimoto, Yoshiji Horikoshi

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    Abstract

    The effect of excitons in Al<inf>x</inf>Ga<inf>1-x</inf>As/GaAs superlattice solar cells has been investigated. We have shown that the superlattice active layers are effective to improve the solar cell performances because of the exciton enhanced photo-absorption. External quantum efficiency spectra show sharp and intense increase at the absorption edge due to excitonic absorption. This result indicates that excitonic photo-absorption can be stabilized at room temperature by using a superlattice structure. Optical properties of superlattice solar cells depend on the superlattice parameters because they determine the excitonic confinement effect, the tunneling effect and the sub-band structure. In this study, we compare external quantum efficiency for solar cells with different superlattice parameters to optimize the structure. The optimal barrier layer thickness is determined to be 1 nm for the Al<inf>0.5</inf>Ga<inf>0.5</inf>As/GaAs superlattice solar cell with 2-μm-thick active layer.

    Original languageEnglish
    Pages (from-to)333-336
    Number of pages4
    JournalJournal of Crystal Growth
    Volume425
    DOIs
    Publication statusPublished - 2015 Jul 28

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    Keywords

    • A3. Molecular beam epitaxy
    • A3. Superlattices
    • B2. Semiconducting gallium arsenide
    • B3. Solar cells

    ASJC Scopus subject areas

    • Condensed Matter Physics
    • Materials Chemistry
    • Inorganic Chemistry

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