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 language | English |
|---|---|
| Pages (from-to) | 4835-4842 |
| Number of pages | 8 |
| Journal | Physical Review B |
| Volume | 43 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1991 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Condensed Matter Physics
Cite this
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 journal › Article
}
TY - JOUR
T1 - Comparison of the phonon spectra of Ge70 and natural Ge crystals
T2 - Effects of isotopic disorder
AU - Fuchs, H. D.
AU - Grein, C. H.
AU - Thomsen, C.
AU - Cardona, M.
AU - Hansen, W. L.
AU - Haller, E. E.
AU - Itoh, Kohei M
PY - 1991
Y1 - 1991
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0000932650&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0000932650&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.43.4835
DO - 10.1103/PhysRevB.43.4835
M3 - Article
VL - 43
SP - 4835
EP - 4842
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 6
ER -