Phonon modes and Raman scattering in GaAs/Ga1−xAlxAs

The phonon modes and the Raman backscattering along the [001] direction in GaAs/${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Al}}_{\mathrm{x}}$As superlattices and heterostructures have been investigated with a linear-chain model. The sample is simulated with a computer, and then exact solutions are obtained numerically. The Raman intensity is calculated with the bond-polarizability approximation. The zone folding, the disorder effect, and the quantum-well confinement have been studied in detail and compared with experiments. In particular, the controversial experimental observations over the disorder effect on the Raman z(xx)z¯ intensity scattered by the topmost longitudinal-acoustical phonon mode is resolved.