Short length scale 'anti-localization' of electrons in a superlattice.

We have used far-infrared absorption to probe the optical conductivity of metallic GaAs:Si sheets imbedded in GaAs by molecular beam epitaxy. An enhancement of the conductivity is observed at short length scales, apparently in response to the suppression at long length scales due to localization and Coulomb interaction effects. However, the spectra do not appear to be quantitatively described by existing theories for long length scales.