Comparison of the phonon spectra of Ge70 and natural Ge crystals: Effects of isotopic disorder

H. D. Fuchs, C. H. Grein, C. Thomsen, M. Cardona, W. L. Hansen, E. E. Haller, K. Itoh

研究成果: Article

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The difference in phonon energies and broadenings between an isotopically enriched crystal of Ge70 (95.9%) and a germanium crystal of natural isotopic composition was measured with high accuracy in first- and second-order Raman spectra (with laser excitation energies of EL=2.41 eV and EL=2.183 eV, respectively) and compared to coherent-potential-approximation and lowest-order perturbation-theory calculations. The energy of the first-order O() phonon shifts up by 4.90.1 cm-1 in the isotopically pure crystal, in good agreement with the calculated value of 4.30.4 cm-1. No broadening due to isotopic disorder was observed for optical phonons at the point [full width at half maximum (FWHM) of 0.990.03 cm-1 at 80 K for both crystals]. However, additional broadening at the W and L point was found in the second-order Raman spectra (FWHM broadening of 6.50.5 cm-1 at the L point). This broadening and the shifts of the acoustic- and optical-phonon peaks in the second-order spectra agree well with calculations of the phonon overtone density of states.

元の言語English
ページ(範囲)4835-4842
ページ数8
ジャーナルPhysical Review B
43
発行部数6
DOI
出版物ステータスPublished - 1991 1 1
外部発表Yes

ASJC Scopus subject areas

  • Condensed Matter Physics

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    Fuchs, H. D., Grein, C. H., Thomsen, C., Cardona, M., Hansen, W. L., Haller, E. E., & Itoh, K. (1991). Comparison of the phonon spectra of Ge70 and natural Ge crystals: Effects of isotopic disorder. Physical Review B, 43(6), 4835-4842. https://doi.org/10.1103/PhysRevB.43.4835