Radial direct bandgap p-i-n GaNP microwire solar cells with enhanced short circuit current

We report the demonstration of dilute nitride heterostructure core/shell microwire solar cells utilizing the combination of top-down reactive-ion etching to create the cores (GaP) and molecular beam epitaxy to create the shells (GaNP). Systematic studies of cell performance over a series of microwir...

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Bibliographic Details
Published in:Journal of applied physics 2016-08, Vol.120 (5)
Main Authors: Sukrittanon, Supanee, Liu, Ren, Pan, Janet L., Breeden, Michael C., Jungjohann, K. L., Tu, Charles W., Dayeh, Shadi A., Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037
Format: Article
Language:English
Subjects:
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
COMPARATIVE EVALUATIONS
ELECTRIC POTENTIAL
ELECTRICAL FAULTS
ELECTRONS
ETCHING
GALLIUM PHOSPHIDES
IONS
MOLECULAR BEAM EPITAXY
MOLECULAR BEAMS
MORPHOLOGY
P-N JUNCTIONS
QUANTUM EFFICIENCY
SHELLS
SOLAR CELLS
SURFACES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
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Summary:We report the demonstration of dilute nitride heterostructure core/shell microwire solar cells utilizing the combination of top-down reactive-ion etching to create the cores (GaP) and molecular beam epitaxy to create the shells (GaNP). Systematic studies of cell performance over a series of microwire lengths, array periods, and microwire sidewall morphologies examined by transmission electron microscopy were conducted to shed light on performance-limiting factors and to optimize the cell efficiency. We show by microscopy and correlated external quantum efficiency characterization that the open circuit voltage is degraded primarily due to the presence of defects at the GaP/GaNP interface and in the GaNP shells, and is not limited by surface recombination. Compared to thin film solar cells in the same growth run, the microwire solar cells exhibit greater short circuit current but poorer open circuit voltage due to greater light absorption and number of defects in the microwire structure, respectively. The comprehensive understanding presented in this work suggests that performance benefits of dilute nitride microwire solar cells can be achieved by further tuning of the epitaxial quality of the underlying materials.
ISSN:0021-8979
1089-7550