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, Kohei M Itoh

Research output: Contribution to journalArticle

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Abstract

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.

Original languageEnglish
Pages (from-to)4835-4842
Number of pages8
JournalPhysical Review B
Volume43
Issue number6
DOIs
Publication statusPublished - 1991
Externally publishedYes

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disorders
Crystals
Full width at half maximum
crystals
Raman scattering
Raman spectra
Germanium
Laser excitation
Excitation energy
shift
Phonons
energy
germanium
phonons
perturbation theory
Acoustics
harmonics
acoustics
Chemical analysis
approximation

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

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

Comparison of the phonon spectra of Ge70 and natural Ge crystals : Effects of isotopic disorder. / Fuchs, H. D.; Grein, C. H.; Thomsen, C.; Cardona, M.; Hansen, W. L.; Haller, E. E.; Itoh, Kohei M.

In: Physical Review B, Vol. 43, No. 6, 1991, p. 4835-4842.

Research output: Contribution to journalArticle

Fuchs, HD, Grein, CH, Thomsen, C, Cardona, M, Hansen, WL, Haller, EE & Itoh, KM 1991, 'Comparison of the phonon spectra of Ge70 and natural Ge crystals: Effects of isotopic disorder', Physical Review B, vol. 43, no. 6, pp. 4835-4842. https://doi.org/10.1103/PhysRevB.43.4835
Fuchs, H. D. ; Grein, C. H. ; Thomsen, C. ; Cardona, M. ; Hansen, W. L. ; Haller, E. E. ; Itoh, Kohei M. / Comparison of the phonon spectra of Ge70 and natural Ge crystals : Effects of isotopic disorder. In: Physical Review B. 1991 ; Vol. 43, No. 6. pp. 4835-4842.
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