Vibrational band modes in germanium: Isotopic disorder-induced Raman scattering

Journal Article · Mon Mar 15 04:00:00 EST 1993 · Physical Review Letters; (United States)

DOI:https://doi.org/10.1103/PhysRevLett.70.1715· OSTI ID:6951969

Fuchs, H D; Etchegoin, P; Cardona, M ^[1]; Itoh, K; Haller, E E ^[2]

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1. Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-7000 Stuttgart 80 (Germany)
2. University of California and Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

We present Raman spectra of natural Ge, [sup 70]Ge, and [sup 70]Ge[sub 0.5] [sup 76]Ge[sub 0.5] in the TO phonon region. The spectrum of the isotopically pure [sup 70]Ge shows only the Raman-active phonon with [ital [rvec k]]=0 ([Gamma]), as required by [ital [rvec k]] conservation. The two isotopically disordered crystals, however, show spectra at the low energy side of the [Gamma] phonon which correspond to isotopic disorder-induced scattering by TO phonons with [ital [rvec k]][ne]0 (band modes). The line shape and the strength of the observed spectra agree with calculations based on the coherent potential approximation and an ansatz for the Raman polarizability. The novel [sup 70]Ge[sub 0.5] [sup 76]Ge[sub 0.5] thus proves to be an ideal crystal to investigate mass disorder effects.

• OSTI ID: 6951969
• Journal Information: Physical Review Letters; (United States), Journal Name: Physical Review Letters; (United States) Vol. 70:11; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ELEMENTS
ENERGY LEVELS
EXCITED STATES
GERMANIUM
ISOTOPE EFFECTS
LASER SPECTROSCOPY
LINE WIDTHS
MEAN-FIELD THEORY
METALS
PHONONS
QUASI PARTICLES
RAMAN SPECTROSCOPY
SPECTRAL SHIFT
SPECTROSCOPY
VIBRATIONAL STATES