Charge-density fluctuations and spatial modulation of heavy- and light-hole-like character in GaAs-AlGaAs(001) superlattices

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Abstract
We have used local pseudopotentials with spin-orbit coupling to illustrate some of the effects occurring in GaAs-AlGaAs (001) superlattices as a result of fluctuations in the widths of the layers. Full account is taken of the microscopic superlattice potential, and states associated with the principal as well as secondary band minima are presented. It is shown that fluctuations of only one monolayer can lead to a complete transfer of probability density into the lowest Γ-related symmetry-induced state. This also applies to states associated with the secondary band minima confined in the hot-electron range of energies. We also show that small fluctuations in layer width can be used to achieve a tunable spatial modulation of heavy- and light-hole-like character within the same superlattice state. We discuss some of the implications of our results for band structure engineering.