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Polarization effects in AlxGa1−xN / GaN superlattices

Published online by Cambridge University Press:  17 March 2011

Erik L. Waldron ,
E. Fred Schubert ,
John W. Graff ,
Andrei Osinsky ,
Michael J. Murphy  and
William F. Schaff
Erik L. Waldron
Affiliation:
Photonics Center, Boston University, Boston, Massachusetts 02215, U.S.A.
E. Fred Schubert
Affiliation:
Photonics Center, Boston University, Boston, Massachusetts 02215, U.S.A.
John W. Graff
Affiliation:
Photonics Center, Boston University, Boston, Massachusetts 02215, U.S.A.
Andrei Osinsky
Affiliation:
Corning Applied Technologies, Woburn, Massachusetts 01801, U.S.A.
Michael J. Murphy
Affiliation:
School of Electrical Engineering, Cornell University, Ithaca, New York 14853, U.S.A.
William F. Schaff
Affiliation:
School of Electrical Engineering, Cornell University, Ithaca, New York 14853, U.S.A.
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Abstract

Room temperature and low temperature photoluminescence studies of AlxGa1−xN/GaN superlattices reveal a red shift of the dominant transition band relative to the bulk GaN bandgap. The shift is attributed to the quantum-confined Stark effect resulting from polarization fields in the superlattices. A theoretical model for the band-to-band transition energies based on perturbation theory and a variational approach is developed. Comparison of the experimental data with this model yields a polarization field of 4.6 × 105 V/cm for room temperature Al0.1Ga0.9N/GaN and 4.5 × 105 V/cm for room temperature Al0.2Ga0.8N/GaN. At low temperatures the model yields 5.3 × 105 V/cm for Al0.1Ga0.9N/GaN and 6.3 × 105 V/cm for Al0.2Ga0.8N/GaN. The emission bands exhibit a blue shift at high excitation densities indicating screening of internal polarization fields by photo-generated free carriers.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 639: Symposium G – GaN and Related Alloys-2000 , 2000 , G11.1
Copyright
Copyright © Materials Research Society 2001

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References

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