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Characterization of Strained Layer Superlattice Solar Cells by X-ray Diffraction and Current-Voltage Measurements

Published online by Cambridge University Press:  31 January 2011

Joshua P. Samberg
Affiliation:
joshsamberg@gmail.com, North Carolina State University, Materials Science and Engineering, Raleigh, North Carolina, United States
Conrad Zachary Carlin
Affiliation:
czcarlin@ncsu.edu
Nadia A. El-Masry
Affiliation:
n_elmasry@ncsu.edu, North Carolina State University, Materials Science and Engineering, Raleigh, North Carolina, United States
Geoffrey K. Bradshaw
Affiliation:
geoff_bradshaw@ncsu.edu, North Carolina State University, Electrical and Computer Engineering, Raleigh, North Carolina, United States
Peter C. Colter
Affiliation:
pccolter@ncsu.edu, North Carolina State University, Electrical and Computer Engineering, Raleigh, North Carolina, United States
Jeffrey L. Harmon
Affiliation:
jlharmon@ncsu.edu, North Carolina State University, Electrical and Computer Engineering, Raleigh, North Carolina, United States
Salah M. Bedair
Affiliation:
bedair@ncsu.edu, United States
John R. Hauser
Affiliation:
hauser@ncsu.edu, North Carolina State University, Electrical and Computer Engineering, Raleigh, North Carolina, United States
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Abstract

InGaAs can be used to enhance the response of solar cells past the 1.43 eV cutoff of GaAs. Strained-layer superlattice (SLS) structures with high indium and phosphorus compositions (up to 35% and 68% respectively) have been grown successfully. SLS solar cells with indium and high phosphorus compositions (up to 15% and 85% respectively) have been grown successfully. The spectral response of the solar cells has been extended to as low as 1.27 eV. This enhancement is also shown by an increase in the short circuit current, with a small reduction in the short circuit voltage as compared to standard GaAs p-n junction for AM1.5 and one sun.

Dark current curves show the extent of recombination in the superlattice. The reverse saturation current in the recombination region (0.2-0.8 V) was determined using a non-linear least squares fitting routine. An Arrhenius plot was generated by finding the reverse saturation current over a temperature range of 300-370 K. The low recombination devices show non-ideality constants of 1.7 with activation energies of 1.3-1.4 eV. The high recombination devices have non-ideality constants (˜2.3) and lower activation energies of 1.1 eV.

Type
Research Article
Copyright
Copyright © Materials Research Society 2010

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References

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