The electronic properties of the miniband and the effect of external electric fields in superlattices

The properties of the lowest-energy miniband in a square-well model superlattice and the electronic properties of this superlattice under an external electric field are studied by simple variational calculations within the concept of the supercell. The calculated width of the miniband (2.4meV) agrees well with the value measured for a GaAs/AlAs superlattice having similar parameters (2meV). For weak fields, the results suggest coherent electron conduction over a few superlattice periods between scattering events, a conclusion which is consistent with experimental results. For strong fields, the formation of Stark ladders is illustrated. © 1990.