INTERFERENCE EFFECTS IN ACOUSTIC-PHONON RAMAN-SCATTERING FROM GAAS ALAS MIRROR-PLANE SUPERLATTICES/

Raman scattering of longitudinal-acoustic phonons has been studied in finite size mirror-plane superlattices (MPSL's) with building blocks S L = (GaAs)(13)/(AlAs)(18) and LS = (AlAs)(18)/(GaAs)(13), arranged to form layer sequences (SL)(m/2)/(LS)(m/2) with different numbers of bui lding blocks m. In contrast to periodic structures (SL)(m), the folded LA-phonon doublets in MPSL's experience pronounced splittings, while satellites appear around the main lines. These effects are due to the interference of the scattering contributions from the different quantu m wells in the sample, and reflect a phase shift introduced by the mir ror-plane symmetry. This phase shift can be tuned by GaAs buffers of d ifferent widths in structures of the type (SL)(m/2)/(GaAs)(n)/(LS)(m/2 ).