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.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, Appl. Phys. Lett. 48, 353 (1986).
I. Akasaki, H. Amano, Y. Koide, K. Hiramatsu, and N. Sawaki, J. Cryst. Growth 98, 209 (1989).
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.
E.T. Yu, G.J. Sullivan, P.M. Asbeck, C.D. Wang, D. Qiao, S.S. Lau, Appl. Phys. Lett. 71, 2794 (1997).
T. Takeuchi, S. Sota, M. Katsuragawa, M. Komori, H. Takeuchi, H. Amano, and I. Akasaki, Jpn. J. Appl. Phys. 36, L 382 (1997).
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.
C. Wetzel, T. Takeuchi, H. Amano, and I. Akasaki, J. Cryst. Growth (1998). in print
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
D.E. Aspnes Phys. Rev. 153, 972 (1967).
D.E. Aspnes and A.A. Studna Phy. Rev. B7, 4605 (1973).
K.W. Böer Survey of Semiconductor physics Van Nostrand Reinhold, New York (1990) p. 968.
F. Bernardini, V. Fiorentini, and D. Vanderbilt, Phys. Rev. Lett. 79, 3958 (1997).
About this article
Cite this article
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