Hybridization of electron, light-hole, and heavy-hole states in InAs/GaSb quantum wells

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.