Phonons in GaAs-Al_xGa_1-xAs superlattices

This paper reviews experimental and theoretical results on superlattice phonons in GaAs-Al_xGa_1-xAs structures. Emphasis is given to the phonon confinement problem and its implications for the understanding of bulk dispersion relations as well as for the structural characterization of superlattices. The dielectric continuum model, subject of controversy over the last few years, is discussed in detail. Finally, a comprehensive analysis underscores the importance of resonance Raman studies for the investigation of exciton physics in quantum wells and illustrates their possible applications for characterization purposes.