Abstract
We report the first account of the optical spectra in the presence of an external electric field of the Si-Ge structure studied by T. P. Pearsall, J. Berk, L. C. Feldman, A. Ourmazd, J. M. Bonar, and J. P. Mannaerts [Phys. Rev. Lett. 28, 729 (1987)]. We show that although there are some novel features in the electronic structure of the finite system, the optical spectrum is very similar to that obtained for an infinite superlattice. The effect of the electric field used in electroreflectance experiments is negligible.