Picosecond Raman Studies of the Electron-Phonon Interactions inAlxGa1−xAs: Nonmonotonic Dependence upon the Alloy Composition

Abstract

The electron–longitudinal-optical- (LO-) phonon interaction in ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ has been studied for the alloy composition ranging from 0.1 to 0.4 by picosecond Raman spectroscopy. We have found that the relative strength of the Fröhlich interaction of the two LO-phonon modes is a nonlinear function, and increases nonmonotonically with the Al composition. The possible origins of these novel results are discussed in terms of nonlinear dielectric theory and ordering in the alloy.