We have investigated the hybridization of the electron states, the light-hole states and the heavy-hole states in InAs/GaSb broken-gap quantum wells. This effect is profound when the InAs layer and the GaSb layer are sufficiently thick such that the electron level lies below the heavy-hole level and the light-hole level at zone center. To calculate the dispersions and the wave functions in these structures we have applied the scattering matrix algorithm to the eight-band k•p model. We have found a hybridization gap as large as 20 meV resulting from the anticrossing of the electron and the light-hole dispersion curves. A multiple anticrossing of the electron states, the light-hole states and the heavy-hole states may occur when the heavy hole level lies in the hybridization gap produced by the electron states and the light-hole states. This unusual hybridization of the three subbands, which behaves differently for the ''spin-up'' and the ''spin-down'' states, has been investigated in details around the anticrossing point. While the electronlike and light holelike states mix strongly, the heavy holelike state may remain unperturbed.

We investigate the hybridization of the electron, heavy-hole and/or light-hole dispersion relations in strained InAs/GaSb quantum wells. In the considered structures, the lowest electron level lies below several hole levels at zero in-plane wave vector k ʈ , so that the anticrossings of subbands produce gaps in the in-plane dispersions. To calculate the electronic band structures of such quantum wells grown on different substrates, we use the eight-band k•p model and the scattering matrix method. We have found that the order of levels at the zone center (k ʈ ϭ0), gap positions and magnitudes can change due to the lattice-mismatched strain. Strain can also enhance the hybridization of electron and light-hole states at k ʈ ϭ0 considerably. In the structure with a thick InAs layer grown on GaSb, we have obtained a negative indirect gap in the in-plane dispersion resulting from the anticrossing of electronlike and highest heavy-hole-like subbands. If the substrate is InAs, the gap becomes direct and positive. This phenomenon can be treated as strain-induced semimetal-semiconductor phase transition.

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