Host isotope effect on the localized vibrational modes of oxygen in isotopically enriched 28Si, 29Si, and 30Si single crystals

Jiro Kato, Kohei M Itoh, Hiroshi Yamada-Kaneta, Hans Joachim Pohl

Research output: Contribution to journalArticle

Abstract

A high-resolution infrared absorption study of the localized vibrational modes (LVM’s) of oxygen in isotopically enriched 28Si, 29Si, and 30Si single crystals is reported. Isotope shifts of LVM frequencies from those in natural Si are clearly observed not only due to the change of the average mass in the nearest-neighbor silicon atoms, but also to the combined effect of the (i) change in Si masses of the second and beyond nearest neighbors and (ii) change in the lattice constants of the host Si crystals. These conclusions have been drawn based on a direct comparison between the experimental results and theoretical calculations assuming harmonic potentials for localized vibrations of oxygen. However, the LVM linewidths of the A2u mode in the enriched samples are much narrower than those in natural Si, despite the fact that the harmonic approximation predicts very little dependence of the width on the host Si isotopic composition. This observation suggests that both anharmonicity and inhomogeneous broadening due to isotopic disorder are playing important roles in the determination of oxygen LVM linewidths. Moreover, a new series of oxygen LVM peaks is observed clearly in the isotopically enriched samples thanks to the small degree of mass disorder.

Original languageEnglish
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume68
Issue number11
DOIs
Publication statusPublished - 2003 Jul 15

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Isotopes
isotope effect
vibration mode
Single crystals
Oxygen
single crystals
oxygen
Linewidth
disorders
Infrared absorption
Silicon
harmonics
Lattice constants
infrared absorption
Atoms
Crystals
vibration
Chemical analysis
high resolution
silicon

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Host isotope effect on the localized vibrational modes of oxygen in isotopically enriched 28Si, 29Si, and 30Si single crystals. / Kato, Jiro; Itoh, Kohei M; Yamada-Kaneta, Hiroshi; Pohl, Hans Joachim.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 68, No. 11, 15.07.2003.

Research output: Contribution to journalArticle

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AB - A high-resolution infrared absorption study of the localized vibrational modes (LVM’s) of oxygen in isotopically enriched 28Si, 29Si, and 30Si single crystals is reported. Isotope shifts of LVM frequencies from those in natural Si are clearly observed not only due to the change of the average mass in the nearest-neighbor silicon atoms, but also to the combined effect of the (i) change in Si masses of the second and beyond nearest neighbors and (ii) change in the lattice constants of the host Si crystals. These conclusions have been drawn based on a direct comparison between the experimental results and theoretical calculations assuming harmonic potentials for localized vibrations of oxygen. However, the LVM linewidths of the A2u mode in the enriched samples are much narrower than those in natural Si, despite the fact that the harmonic approximation predicts very little dependence of the width on the host Si isotopic composition. This observation suggests that both anharmonicity and inhomogeneous broadening due to isotopic disorder are playing important roles in the determination of oxygen LVM linewidths. Moreover, a new series of oxygen LVM peaks is observed clearly in the isotopically enriched samples thanks to the small degree of mass disorder.

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