Nature of the band gap (direct versus indirect) of short-period (GaAs)n/(AlAs)n superlattices grown along the [111] confinement direction

We report on spectroscopic experimental evidence of type II band alignment in a (GaAs)6/(AlAs)6 superlattice grown by molecular beam epitaxy along the (111) direction. This result is in contrast to recent theoretical calculations predicting that the (GaAs)n/(AlAs)n superlattices grown along the (111) direction should be direct for all n’s.