Raman effect in tunneling-transparent superlattices

The cross section for the Raman scattering of light in electron superlattices is calculated, including a finite probability for tunneling between layers. In the long-wavelength approximation, i.e., for the case in which the momentum transfer is much smaller than the reciprocal of the superlattice constant, it is shown that an unscreened component of single-particle scattering arises when there is a finite tunneling. This unscreened component may be substantially greater than the scattering cross section in a lattice without tunneling. Competing unscreened-scattering mechanisms, unrelated to tunneling, are analyzed