Raman and resonance Raman spectroscopic techniques have been utilized to study the phenomenon of spontaneous ordering in epitaxial ${\mathrm{Ga}}_{0.52}$${\mathrm{In}}_{0.48}$P grown on (001) GaAs substrates at different temperatures. Raman selection rules suggest larger deviations from cubic zinc-blende symmetry for samples exhibiting a greater degree of ordering. Raman excitation profiles show a redshift and broadening of the resonance peak as the samples become more ordered. In addition, the anisotropy of the absorption coefficients along the [110] and [11¯0] crystallographic directions in the rhombohedral phase of the ordered material enables us to estimate the crystal-field splitting. Our results support the recently proposed microstructural model for ordering in these alloys.

• Received 26 July 1993

DOI:https://doi.org/10.1103/PhysRevB.48.17591