Anomalous low energy phonon dispersion in bulk silicon-germanium observed by inelastic x-ray scattering

R. Yokogawa*, H. Takeuchi, Y. Arai, I. Yonenaga, M. Tomita, H. Uchiyama, T. Watanabe, A. Ogura

*この研究の対応する著者

研究成果: Article査読

6 被引用数 (Scopus)

抄録

We report on an anomalous mode distinct from both optical and acoustic modes in phonon dispersion curves of bulk Si1-xGex alloy with x taking the values of 0.16, 0.32, 0.45, and 0.72. The anomalous mode at approximately 13 meV was observed directly using inelastic x-ray scattering along the Γ-X ([00q]) direction. The phonon dispersion relations of the anomalous mode indicate that there was no momentum dependence, similar to those of the longitudinal and transverse optical modes (Ge-Ge, Si-Ge, and Si-Si modes). In contrast to the acoustic and optical phonon modes, the energy of the anomalous mode shows no Ge fraction dependence. The molecular dynamics simulation corroborates that the Ge-Ge pairs or Ge atom clusters, which are surrounded by Si atoms, provide the anomalous mode, which is unique to the alloy structure. It has been suggested that such a localized vibration mode with no propagation significantly affects the acoustic modes, leading to low thermal conductivity in the SiGe alloy.

本文言語English
論文番号242104
ジャーナルApplied Physics Letters
116
24
DOI
出版ステータスPublished - 2020 6 15

ASJC Scopus subject areas

  • 物理学および天文学(その他)

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