J. Groenen et al., OPTICAL-PHONON BEHAVIOR IN GA1-XINXAS - THE ROLE OF MICROSCOPIC STRAINS AND IONIC PLASMON COUPLING, Physical review. B, Condensed matter, 58(16), 1998, pp. 10452-10462
We present an experimental and theoretical investigation of long-wavel
ength optical-phonon behavior in Ga1-xInxAs alloys. We propose a model
which accounts quantitatively for both phonon frequencies and Raman i
ntensities. The transverse-optical-phonon behavior is shown to be dete
rmined by mass disorder and microscopic strains. It is shown that Rama
n scattering provides a means of measuring local bond distortions in m
ixed crystals. Coupling by the macroscopic ionic polarization is shown
to determine the longitudinal optical phonon behavior. The model acco
unts for the so-called anomalies of the Raman intensities and oscillat
or strengths observed in Ga1-xInxAs. Our analysis is supported by a th
orough Raman-scattering study. The frequencies, Raman intensities and
symmetries of both the transverse- and longitudinal-optical modes have
been determined accurately over the whole compositional range, by usi
ng different crystal orientations ([001], [110], and [111]). [S0163-18
29(98)07540-7].