Piezoelectric Quantization in GaInN thin Films and Multiple Quantum Well Structures


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.

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  1. 1.

    H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, Appl. Phys. Lett. 48, 353 (1986).

    CAS  Article  Google Scholar 

  2. 2.

    I. Akasaki, H. Amano, Y. Koide, K. Hiramatsu, and N. Sawaki, J. Cryst. Growth 98, 209 (1989).

    CAS  Article  Google Scholar 

  3. 3.

    I. Akasaki, N. Sawaki, K. Hiramatsu, and H. Goto. Report of Priority Area Research Program, supp. by Ministry of Edu. Sci. Culture of Jap (in japanese) (1988) p. 106 ff.

    Google Scholar 

  4. 4.

    E.T. Yu, G.J. Sullivan, P.M. Asbeck, C.D. Wang, D. Qiao, S.S. Lau, Appl. Phys. Lett. 71, 2794 (1997).

    CAS  Article  Google Scholar 

  5. 5.

    T. Takeuchi, S. Sota, M. Katsuragawa, M. Komori, H. Takeuchi, H. Amano, and I. Akasaki, Jpn. J. Appl. Phys. 36, L 382 (1997).

    Google Scholar 

  6. 6.

    H. Amano, T. Takeuchi, S. Sota, H. Sakai, and I. Akasaki (Eds. F. Ponce, T.D. Moustakas, I. Akasaki, and B. Monemar), Mater. Res. Soc. 449, (1997) p. 1143.

    CAS  Article  Google Scholar 

  7. 7.

    C. Wetzel, T. Takeuchi, H. Amano, and I. Akasaki, J. Cryst. Growth (1998). in print

    Google Scholar 

  8. 8.

    C. Wetzel, H. Amano, I. Akasaki, T. Suski, J.W. Ager, E.R. Weber, E.E. Haller, and B.K. Meyer, Nitride Semiconductors, Eds. S.P. DenBaars, B.K. Meyer, S. Nakamura, F.A. Ponce, T. Strite, Mater. Res. Soc. 482 (1998). in print

  9. 9.

    D.E. Aspnes Phys. Rev. 153, 972 (1967).

    CAS  Article  Google Scholar 

  10. 10.

    D.E. Aspnes and A.A. Studna Phy. Rev. B7, 4605 (1973).

    CAS  Article  Google Scholar 

  11. 11.

    K.W. Böer Survey of Semiconductor physics Van Nostrand Reinhold, New York (1990) p. 968.

    Google Scholar 

  12. 12.

    F. Bernardini, V. Fiorentini, and D. Vanderbilt, Phys. Rev. Lett. 79, 3958 (1997).

    CAS  Article  Google Scholar 

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Wetzel, C., Takeuchi, T., Amano, H. et al. Piezoelectric Quantization in GaInN thin Films and Multiple Quantum Well Structures. MRS Online Proceedings Library 512, 181–186 (1998). https://doi.org/10.1557/PROC-512-181

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