Selectivity of resonant Raman scattering inInAsxP1−xsolid solutions

The resonances of several structures (1LO, 2LO, disorder-activated TO, disorder-activated TA, disorder-activated LA, and local mode) in the Raman spectra of $\mathrm{In}{\mathrm{As}}_x{\mathrm{P}}_{1-x}$ alloys are investigated around the energy of the $E_1$ critical edge. Comparison with the resonances in mechanically perturbed InAs allows discrimination between the perturbations induced by either structural or chemical disorder inherent in the alloys. Large electron-phonon coupling for the longitudinal modes is seen, and the energy of the resonances is found to be dependent on the coherence length of the vibrational modes.