Anticrossing semiconducting band gap in nominally semimetallic InAs/GaSb superlattices

While (InAs)(n)/(GaSb)(n) (001) superlattices are semiconducting for nn(c) the InAs electron level e(InAs) is below the GaSb hole level h(GaSb), so the system is converted to a nominal semimetal. At nonzero in-plane wave vectors (k(parallel to)not equal 0), however, the wave functions e(InAs) and h(GaSb) have the same symmetry, so they anticross. This opens up a hybridization gap'' at some k(parallel to)=k(parallel to)*. 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.