Phonons in semiconductor planar microcavities: A Raman scattering study

We present a detailed Raman-scattering study of optical and folded-acoustic phonons in semiconductor planar microcavities. The GaAs-like optical-phonon Raman spectra consists of a series of peaks due to the microcavity ``interface-phonon'' band, comprising both distributed Bragg reflector and embedded quantum-well modes. Finite-size effects are shown, including the observation of surface vibrations, wave-vector quantization leading to a discretization of the interface-mode bands, and relaxation of the conservation of the latter in scattering processes. Phonon energies, their in-plane mode dispersion, and Raman-scattering selection rules can be well accounted for by symmetry considerations and calculations of the phonon spectra and electrostatic potentials based on a dielectric continuum model. A further doubling of the folded acoustic-phonon Raman peaks is observed in a multiple-quantum-well filled microcavity, demonstrating the presence of forward-scattering processes in backscattering geometries with Bragg mirrors. These results highlight the potentialities of Raman scattering as a material sensitive tool to access the photon mode structure of photonic devices. {} 1996 The American Physical Society.