Hostname: page-component-8448b6f56d-m8qmq Total loading time: 0 Render date: 2024-04-19T12:33:22.178Z Has data issue: false hasContentIssue false
  • English
  • Français

Phonons and Free Carriers in a Strained Hexagonal GaN-AlN Superlattice Measured by Infrared Ellipsometry and Raman Spectroscopy

Published online by Cambridge University Press:  03 September 2012

M. Schubert ,
A. Kasic ,
T.E. Tiwald ,
J.A. Woollam ,
V. Harle  and
F. Scholz
M. Schubert
Affiliation:
Center for Microelectronic and Optical Materials Research, University of Nebraska, Lincoln, NE 68588-0511, U.S.A Abteilung Halbleiterphysik, Institut fur Experimentelle Physik II, Universitat Leipzig, Vor dem Hospitaltor 1, D-04103 Leipzig, Germany
A. Kasic
Affiliation:
Abteilung Halbleiterphysik, Institut fur Experimentelle Physik II, Universitat Leipzig, Vor dem Hospitaltor 1, D-04103 Leipzig, Germany
T.E. Tiwald
Affiliation:
Center for Microelectronic and Optical Materials Research, University of Nebraska, Lincoln, NE 68588-0511, U.S.A
J.A. Woollam
Affiliation:
Center for Microelectronic and Optical Materials Research, University of Nebraska, Lincoln, NE 68588-0511, U.S.A
V. Harle
Affiliation:
4. Physikalisches Institut, Universitat Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany now with Osram Opto Semiconductors, Wernerwerkstr., D-93049 Regensburg, Germany
F. Scholz
Affiliation:
4. Physikalisches Institut, Universitat Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
Get access

Abstract

Phonon and free-carrier effects in a strained hexagonal (α) {GaN}l-{AlN}m superlattice (SL) heterostructure (l = 8 nm, m = 3 nm) are studied by infrared spectroscopic ellipsometry (IRSE) and micro (µ)-Raman scattering. Growth of the heterostructures was performed by metal-organic vapor phase epitaxy (MOVPE) on (0001) sapphire. An unstrained 1 µm-thick α-GaN layer was deposited prior to the SL. SL phonon modes are identified combining results from both IRSE and µ-Raman techniques. The shift of the GaN-sublayer phonon modes is used to estimate an average compressive SL stress of σxx ∼ - 4.3 GPa. The IRSE data reveal a free-carrier concentration of ne ∼ 5×1018 cm−3 within the undoped SL GaN-sublayers. According to the vertical carrier confinement, the free-carrier mobility is anisotropic, and the lateral mobility ( µ⊥ ∼ 400 cm2/Vs, polarization E⊥c-axis) exceeds the vertical mobility (µ∥ ∼ 24 cm2/Vs, E∥c) by one order of magnitude.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 595: Symposium W – GaN and Related Alloys - 1999 , 1999 , F99W11.39
Copyright
Copyright © Materials Research Society 1999

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Orton, J. W., Rep. Prog. Phys. 61, 1 (1998).Google Scholar
2. Gleize, J., Demangeot, F., Frandon, J., Renucci, M. A., Widmann, F. and Daudin, B., Appl. Phys. Lett. 74, 703 (1999).Google Scholar
3. Polian, A., Grimsditch, M. and Grzegory, I., J. Appl. Phys. 79, 3343 (1996).Google Scholar
4. Davydov, V. Yu., Averkiev, N. S., Goncharuk, I. N., Nelson, D. K., Nikitina, I. P., Polkovnikov, A. S., Smirnov, A. N., Jacobson, M. A., and Semchinova, O. K., J.Appl. Phys. 82, 5097 (1997).Google Scholar
5. Schubert, M., Kasic, A., Tiwald, T. E., Off, J., Kuhn, B., Scholz, F., MRS Internet J. Nitride Semicond. Res. 4, 11 (1999).Google Scholar
6. Kasic, A., Schubert, M., Einfeldt, S., Hommel, D., unpublished.Google Scholar
7. Tiwald, T. E., Woollam, J.A., Zollner, S., Christiansen, J., Gregory, R. B., Wetteroth, T., Wilson, S. R. and Powell, A. R., Phys. Rev. B 60, 11464 (1999).Google Scholar
8. Scholz, F., Härle, V., Bolay, H., Steuber, F., Kaufmann, B., Reyer, G., Dörnen, A., Gfrörer, O., Im, S.-J., Hangleiter, A., Solid State Electron. 41, 141 (1997).Google Scholar
9. Schubert, M., Tiwald, T. E. and Herzinger, C. M., Phys. Rev. B 61 (March 15. 2000).Google Scholar
10. Kozawa, T., Kachi, T., Kano, H., Taya, Y., Hashimoto, M., Koide, N. and Manabe, K., J. Appl. Phys. 75, 1098 (1994).Google Scholar