Anticrossing semiconducting band gap in nominally semimetallic InAs/GaSb superlattices

While (InAs)n/(GaSb)n (001) superlattices are semiconducting for nnc the InAs electron level eInAs is below the GaSb hole level hGaSb, so the system is converted to a nominal semimetal. At nonzero in-plane wave vectors (k|| [not equal] 0), however, the wave functions eInAs and hGaSb have the same symmetry, so they anticross. This opens up a "hybridization gap" at some k||=k*||. Using a pseudopotential plane-wave approach as well as a (pseudopotential fit) eight-band k·p approach, we predict the hybridization gap and its properties such as wave-function localization and out-of-plane dispersion. We find that recent model calculations underestimate this gap severely.