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Temperature Dependent Characterization of Imbedded InAs Quantum Dots in GaAs Superlattice Solar Cell Structures by High Resolution X-ray Diffraction

Published online by Cambridge University Press:  13 June 2012

Josephine J. Sheng
Affiliation:
Department of Nanoscience and Microsystems, University of New Mexico, Albuquerque, New Mexico.
David. C. Chapman
Affiliation:
Air Force Research Laboratory, Albuquerque, New Mexico.
David M. Wilt
Affiliation:
Air Force Research Laboratory, Albuquerque, New Mexico.
Stephen J. Polly
Affiliation:
NanoPower Research Laboratory, Rochester Institute of Technology, Rochester, New York.
Christopher G. Bailey
Affiliation:
NanoPower Research Laboratory, Rochester Institute of Technology, Rochester, New York.
Christopher Kerestes
Affiliation:
NanoPower Research Laboratory, Rochester Institute of Technology, Rochester, New York.
Seth M. Hubbard
Affiliation:
NanoPower Research Laboratory, Rochester Institute of Technology, Rochester, New York.
Sang M. Han
Affiliation:
Department of Nanoscience and Microsystems, University of New Mexico, Albuquerque, New Mexico. Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico.
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Abstract

The insertion of nanostructured materials (such as quantum wells, wires, and dots) into the intrinsic region of p-i-n solar cells introduces an intermediate band within the bandgap of the host material. It has been shown that the sub-bandgap conversion provided by the nanostructured materials, enhances the short circuit current as well as the overall efficiency of InAs quantum dots (QD) imbedded in GaAs superlattice (SL) solar cells [1]. As a contender for space applications, it is necessary to subject these solar cell structures to temperatures encountered in the Low Earth Orbit (LEO), probing for any material degradation. Herein, we focus on temperature dependent characterization using high resolution X-ray diffraction (HRXRD) of InAs QD enhanced GaAs solar cell structures with varying growth parameters. The structures characterized can be classified into three groups: (1) GaP strain compensation coverage, (2) GaAs barrier coverage, and (3) InAs coverage for QD formation. HRXRD rocking curves of each structure focusing around the GaAs peak are analyzed at a range of temperatures up to 200˚C. Although no noticeable shifts in the SL peaks are detected, interfacial diffusion decreased the resolution of fringes produced by reflections at the SL interfaces in test structures with varying InAs QD coverage. Unbalanced strain in the same structures shows a distortion in the GaAs peaks.

Type
Articles
Copyright
Copyright © Materials Research Society 2012

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References

REFERENCES

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