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Multijunction Ga 0.5 In 0.5 P/GaAs solar cells grown by dynamic hydride vapor phase epitaxy
Author(s) -
Schulte Kevin L.,
Simon John,
Ptak Aaron J.
Publication year - 2018
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3027
Subject(s) - solar cell , epitaxy , heterojunction , optoelectronics , materials science , electroluminescence , band gap , open circuit voltage , hydride , gallium arsenide , tandem , analytical chemistry (journal) , voltage , chemistry , nanotechnology , electrical engineering , metal , engineering , layer (electronics) , chromatography , metallurgy , composite material
We report the development of Ga 0.5 In 0.5 P/GaAs monolithic tandem solar cells grown by dynamic hydride vapor phase epitaxy, a III‐V semiconductor growth alternative to metalorganic vapor phase epitaxy with the potential to reduce growth costs. The tandem device consists of 3 components: a 1.88 eV band gap ( E G ) Ga 0.5 In 0.5 P top cell, a p‐Ga 0.5 In 0.5 P/n‐GaAs tunnel junction, and a 1.41 eV rear heterojunction GaAs cell. The open circuit voltage ( V OC ) and fill factor are 2.40 V and 88.4%, respectively, indicative of high material quality. Electroluminescence measurements show that the individual V OC of the top and bottom cell are 1.40 and 1.00 V, respectively, yielding E G ‐voltage offsets ( W OC ) of 0.48 and 0.41 V. The W OC of the top cell is higher because of an unpassivated front surface rather than the bulk material quality. The Ga 0.5 In 0.5 P top cell limits the current of this series‐connected device for this reason to a short‐circuit current density ( J SC ) of 11.16 ± 0.15 mA/cm 2 yielding an overall efficiency of 23.7% ± 0.3%. We show through modeling that thinning the emitter will improve the present result, with a clear pathway toward 30% efficiency with the existing material quality. This result is a promising step toward the realization of high‐efficiency III‐V multijunction devices with reduced growth cost.

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