Raman analysis of electron-phonon interactions in GaN films

L. Bergman, M. D. Bremser, J. A. Christman, S. W. King, R. F. Davis, Robert Nemanich

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Scopus citations

Abstract

Raman analysis of film quality, phonon-plasmon coupling, and phonon-exciton interaction in GaN films with varying Si doping levels is presented. The films exhibit a small stress component ≈0.1 GPa, calculated from the frequency shift of the E2 mode. No correlation between the stress and the doping concentration was found. No forbidden Raman lines were detected in the spectra, implying high quality oriented films. The Raman lineshape of the E2 mode is a Lorentzian with similar linewidths at room temperature and at 10K indicating a homogeneous lifetime broadening mechanism which is not significantly affected by the change in temperature. The linewidth is also independent of Si concentration. The phonon-plasmon mixed frequency modes were calculated to be at (ω - = 86 cm -1 and at ω + = 741 cm - 1. The modes are not present in the spectra and the only effect of the plasmons is a change of the A1(LO) lineshape. Analysis of the A1(LO) line indicated a uniform spatial doping distribution. A resonance effect was observed for the symmetry-allowed A1(LO) mode at T = 10K with sub bandgap excitation light. The resonance interaction is consistent with the free exciton model.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
EditorsF.A. Ponce, T.D. Moustakas, I. Akasaki, B.A. Monemar
PublisherMaterials Research Society
Pages725-730
Number of pages6
Volume449
StatePublished - 1997
Externally publishedYes
EventProceedings of the 1996 MRS Fall Symposium - Boston, MA, USA
Duration: Dec 2 1996Dec 6 1996

Other

OtherProceedings of the 1996 MRS Fall Symposium
CityBoston, MA, USA
Period12/2/9612/6/96

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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  • Cite this

    Bergman, L., Bremser, M. D., Christman, J. A., King, S. W., Davis, R. F., & Nemanich, R. (1997). Raman analysis of electron-phonon interactions in GaN films. In F. A. Ponce, T. D. Moustakas, I. Akasaki, & B. A. Monemar (Eds.), Materials Research Society Symposium - Proceedings (Vol. 449, pp. 725-730). Materials Research Society.