Abstract

There is much current interest in GaAs-(AlGa) As heterojunctions as model semiconductor systems of reduced dimensionality. One of the striking features of GaAs-(AlGa) As quantum well heterostructures is the strong enhancement of exciton properties. We have recently discovered that the resonant Raman scattering (RRS) method has novel applications in the study of quasi-two dimensional excitons in GaAs quantum wells. The resonantly enchanced Raman signal can be observed even in the presence of a large luminescence background. RRS also shows extremely high contrast as a spectroscopic tool for higher-lying exciton states where absorption and excitation spectroscopy are less effective. In addition, RRS provides new insight into the electron-phonon interactions and vibrational properties unique to this layered system. The Raman spectra show direct evidence of the degree of exciton localization within the quantum wells. Also, the shape of the resonant Raman profile can be used to determine exciton-phonon scattering channels. Polarization selection rules for the scattered light have established the effects of reduced dimensionality on the optical lattice vibrations and allow comparison between deformation potential and Frohlich exciton-phonon interactions.

© 1984 Optical Society of America