Deep levels in type-II InAs/GaSb superlattices.

The theory of sp 3 -bonded substitutional deep impurity levels is extended to type-II gap-misaligned InAs/GaSb superlattices. The theory predicts that some shallow impurities (donors or acceptors) in either bulk GaSb can become deep traps in a thin-layer superlattice. This happens because the deep levels associated with point defects in either InAs Or GaSb layers (when measured relative to the valence-band maximum of InAs) are much less sensitive to changes of the layer thicknesses of the superlattice than the superlattice band edges