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Raman-scattering probe of anharmonic effects due to temperature and composition in InGaN

Authors

  • J. F. Kong,

    Corresponding author
    1. School of Science, Shanghai Institute of Technology, 100 Hai Quan Road, Shanghai 201418, P. R. China
    • Phone: 86-21-60873193, Fax: 86-21-60873193
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  • W. Z. Shen,

    1. Laboratory of Condensed Matter Spectroscopy and Opto-Electronic Physics, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, P. R. China
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  • Q. X. Guo

    1. Synchrotron Light Application Center, Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502, Japan
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Abstract

We have carried out a detailed investigation of temperature-dependent micro-Raman scattering on In1 − xGaxN films with different Ga compositions (0.06 ≤ χ ≤ 0.91). The observed phonon frequency downshift and linewidth broadening with increasing temperature of A1(LO) and E2(high) modes can be well explained by a model taking into account the contributions of the thermal expansion, the lattice-mismatch-induced strain, and the anharmonic phonon processes. We have elucidated the variation with Ga composition of the contribution of the three- and four-phonon processes in the anharmonic effect. It is found that with increasing Ga composition the three-phonon process increases over the four-phonon process. The variation in the relative contribution from three- and four-processes can be further attributed to the diversification of structural properties and phonon density of states in InGaN.

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