Growth of lattice-matched GaInAsP grown on vicinal GaAs(001) substrates within the miscibility gap for solar cells

The growth of quaternary Ga0.68In0.32As0.35P0.65 by metal-organic vapor phase epitaxy is very sensitive to growth conditions because the composition is within a miscibility gap. In this investigation, we fabricated 1µm-thick lattice-matched GaInAsP films grown on GaAs(001) for application to solar c...

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Bibliographic Details
Published in:Journal of crystal growth 2017-01, Vol.458, p.1-7
Main Authors: Oshima, Ryuji, France, Ryan M., Geisz, John F., Norman, Andrew G., Steiner, Myles A.
Format: Article
Language:English
Subjects:
A3. Metalorganic vapor phase epitaxy
Adatoms
Antireflection coatings
Atomic force microscopy
B1. Alloys
B2. Semiconducting quaternary alloys
B3. Solar cells
Chemical compounds
Current density
Diffusion
Diffusion effects
Epitaxial growth
Gallium arsenide
Gallium indium arsenide phosphide
Lattice matching
Metalorganic chemical vapor deposition
Miscibility
Miscibility gap
Photovoltaic cells
Roughness
Short circuits
Solar cells
Substrates
Surface diffusion
Temperature
Thick films
Thin films
Transmission electron microscopy
Vapor phase epitaxy
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Summary:The growth of quaternary Ga0.68In0.32As0.35P0.65 by metal-organic vapor phase epitaxy is very sensitive to growth conditions because the composition is within a miscibility gap. In this investigation, we fabricated 1µm-thick lattice-matched GaInAsP films grown on GaAs(001) for application to solar cells. The growth temperature and substrate miscut are varied in order to characterize the effect of the surface diffusion of adatoms on the material quality of alloys. Transmission electron microscopy and two-dimensional in-situ multi-beam optical stress determine that growth temperatures of 650°C and below enhance the formation of the CuPtB atomic ordering and suppress material decomposition, which is found to occur at the growth surface. The root-mean-square (RMS) roughness is reduced from 33.6nm for 750 °C to 1.62nm for 650°C, determined by atomic force microscopy. Initial investigations show that the RMS roughness can be further reduced using increased miscut angle, and substrates miscut toward (111)A, leading to an RMS roughness of 0.56nm for the sample grown at 600°C on GaAs miscut 6° toward (111)A. Using these conditions, we fabricate an inverted hetero-junction 1.62eV Ga0.68In0.32As0.35P0.65 solar cell without an anti-reflection coating with a short-circuit current density, open-circuit voltage, fill factor, and efficiency of 12.23mA/cm2, 1.12V, 86.18%, and 11.80%, respectively. •The GaInAsP films was fabricated on GaAs by MOVPE for application to solar cells.•The correlation between the phase separation and the atomic ordering was studied.•The low growth temperature enhanced the formation of the CuPtB atomic ordering.•The phase separation was suppressed using low growth temperature.•The cell efficiency of 11.8% was achieved for the 1.62eV GaInAsP solar cell.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2016.10.025