InAs-GaSb superlattice energy structure and its semiconductor-semimetal transition

Abstract
We performed a band calculation, based on the LCAO (linear combination of atomic orbitals) method, for the InAs-GaSb superlattice. Of possible semiconductor combinations the InAs-GaSb is of special interest because of indications that at a heterojunction interface the bottom of the conduction band of InAs lies below the top of the valence band of GaSb. Our results show that the InAs-GaSb superlattice is a semiconductor when the layers of the constituent materials are thin, and becomes a semimetal when the layer thicknesses are increased. The critical InAs thickness for this transition is approximately 115 Å, over which the electrons from the valence band of GaSb "flood" the conduction band of InAs. For the thick-layer limit, we treat the problem in a Fermi-Thomas approximation.

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