The LO-phonon resonant Raman scattering is studied in GaAs/${\mathrm{Al}}_{0.32}$${\mathrm{Ga}}_{0.68}$As Bragg-confining structures at low temperatures. Comparative studies are made on a GaAs/${\mathrm{Al}}_{0.32}$${\mathrm{Ga}}_{0.68}$As superlattice and on a bulk ${\mathrm{Al}}_{0.3}$${\mathrm{Ga}}_{0.7}$As crystal. A strong scattering intensity is observed in the spectral range of the (${\mathit{e}}_{\mathit{B}}$:${\mathrm{hh}}_{\mathit{B}}$)1S, (${\mathrm{e}}_{\mathrm{B}}$:${\mathrm{lh}}_{\mathit{B}}$)1S Bragg-confined excitions and the (${\mathit{e}}_1$:${\mathrm{hh}}_1$)1S superlattice exciton. The Raman profiles, namely, the scattering intensity versus exciting laser energy (in the respective spectral ranges) are characterized by a large outgoing-beam/incoming-beam intensity ratio. These profiles are analyzed in terms of a model based on exciton confinement, on the anisotropy of its 1S wave function (which defines its dimensionality), and on its scattering by interface and alloy potential fluctuations. The (${\mathit{e}}_{\mathit{B}}$:${\mathrm{hh}}_{\mathit{B}}$)1S exciton is thus found to be virtually two-dimensional, while the (${\mathit{e}}_{\mathit{B}}$:${\mathrm{lh}}_{\mathit{B}}$)1S and (${\mathit{e}}_1$:${\mathrm{hh}}_1$)1S excitons are intermediate between two and three dimensions. The dimensionality is found to be related to the degree of confinement.

• Received 17 March 1994

DOI:https://doi.org/10.1103/PhysRevB.50.5305