Raman scattering by interface phonons in GaAs-AlAs multiple-quantum-well structures: Correlation between Raman and high-resolution electron microscopy results

The effects of shallow impurity and interface roughness on resonant Raman scattering by interface phonons in GaAs-AlAs multiple quantum-well structures have been studied. By correlating the Raman results with observations by high-resolution electron microscopy, it has been demonstrated that Raman scattering from interface phonons depends strongly on the sample quality. For a relatively smooth interface with about 1-2 monolayers of interface roughness, the Raman signal is governed primarily by the impurity if the impurity concentration inside the GaAs layers is greater than about 2×10 ¹⁶ cm^-3. On the other hand, for nominally undoped quantum-well structures, the Raman signal can be dominated by interface roughness if the interfaces are sufficiently distorted.