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Piezoelectric Quantization in GaInN thin Films and Multiple Quantum Well Structures

Published online by Cambridge University Press:  10 February 2011

Christian Wetzel ,
Tetsuya Takeuchi ,
Hiroshi Amano  and
Isamu Akasaki
Christian Wetzel
Affiliation:
High Tech Research Center and Department of Electrical and Electronic Engineering, Meijo University, 1–501 Shiogamaguchi, Tempaku-ku, Nagoya 468–8502, Japan.
Tetsuya Takeuchi
Affiliation:
High Tech Research Center and Department of Electrical and Electronic Engineering, Meijo University, 1–501 Shiogamaguchi, Tempaku-ku, Nagoya 468–8502, Japan.
Hiroshi Amano
Affiliation:
High Tech Research Center and Department of Electrical and Electronic Engineering, Meijo University, 1–501 Shiogamaguchi, Tempaku-ku, Nagoya 468–8502, Japan.
Isamu Akasaki
Affiliation:
High Tech Research Center and Department of Electrical and Electronic Engineering, Meijo University, 1–501 Shiogamaguchi, Tempaku-ku, Nagoya 468–8502, Japan.
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Abstract

Details of the electronic bandstructure in pseudomorphic Gal-xInxN/GaN single heterostructures (0 < x < 0.22) are studied. In photocarrier modulated reflectance strong modulation of the density of states (Franz-Keldysh oscillations) is found due to a piezoelectric field of about 0.6 MV/cm in the strained layer. No excitons are expected to form in the presence of this field. Studying the composition dependence we determine a piezoelectric coefficient ∂|P|/∂εzz = 0.46 C/m2 and extrapolate a spontaneous polarization in GaN |Peq| = 3.9 mC/m2. Photoreflection indicates the presence of localized tail states 50 – 100 meV below the bandgap which are well explained by the Franz-Keldysh effect involving k non-conserving transitions in the large electric field. Luminescence is found to originate in these electric field induced states. The derived bandgap energies can be approximated by an interpolation yielding bowing parameters b = 2.6 eV (photoreflection) and b = 3.2 eV (luminescence) for pseudomorphic films with 0.07 ≤ x ≤ 0. 22. These findings may affect interpretation of device performance.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 512: Symposium F – Wide Bandgap Semiconductors for High Power, High Frequency , 1998 , 181
Copyright
Copyright © Materials Research Society 1998

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References

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