Anticrossing semiconducting band gap in nominally semimetallic InAs/GaSb superlattices

While (InAs)(n)/(GaSb)(n) (001) superlattices are semiconducting for n<n(c) approximate to 28 ML, for n>n(c) the InAs electron level e(InAs) is below t he GaSb hole level h(GaSb), so the system is converted to a nominal semimet al. 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 anti cross. This opens up a "hybridization gap'' at some k(parallel to)=k(parall el to)*. Using a pseudopotential plane-wave approach as well as a (pseudopo tential fit) eight-band k.p approach, we predict the hybridization gap and its properties such as wave-function localization and out-of-plane dispersi on. We find that recent model calculations underestimate this gap severely.