Infrared optical responses of wurtzite InxGa1 - XN thin films with porous surface morphology

P. Yew, S. C. Lee, S. S. Ng, H. Abu Hassan, W. L. Chen, T. Osipowicz, M. Q. Ren

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3 Citations (Scopus)


Room temperature infrared (IR) optical responses of wurtzite indium gallium nitride (InxGa1 - xN) in the composition range of 0.174 ≤ x ≤ 0.883 were investigated by the polarized IR reflectance spectroscopy. Analyses of the amplitudes of oscillation fringes in the non-reststrahlen region revealed that the high frequency dielectric constants of the samples were unusually smaller than the values predicted from the Clausius-Mossotti relation. This odd behavior was attributed to the porous surface morphology of the InxGa1 - xN samples. The E1 optical phonon modes of the InxGa1 - xN were deduced from the composition dependent reststrahlen features. The obtained values were compared to those calculated through the modified random element iso-displacement (MREI) model. The deviation between the measured data and the MREI model prediction were explained in detail from the aspects of strain, thermal expansion and anharmonic phonon-coupling. Finally, it was found that the large discrepancy of the E1(LO) mode is mainly attributed to the effects of the longitudinal phonon-plasmon coupling.

Original languageEnglish
Pages (from-to)334-341
Number of pages8
JournalThin Solid Films
Publication statusPublished - 2016 Mar 31

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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