Resonant Raman scattering at the saddle-point singularity inInxGa1−xAs

Abstract

Resonant Raman scattering results are reported at the $E_1$ critical point of mixed ${\mathrm{In}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As crystals. The scattering amplitude shows resonance enhancement which diminishes with increasing x, corresponding to increasing compositional disorder in the alloy. For large disorder the Van Hove singularities are smeared out which is reflected in the light scattering.