Hetero n-i-p-i superlattices combine the interesting and useful tunability of conventional doping superlattices ("n-i-p-i crystals") with the high mobility and the weakly broadened subband structure of modulation-doped heterostructure superlattices. The recombination rate for injected electrons and holes can be very low in these systems due to the spatial separation of electrons and holes. Consequently, large non-equilibrium charge carrier concentrations can be maintained. These charge carrier distributions affect significantly the superlattice potential. We present calculations of the electron and hole subbands taking into account the self-consistent potentials of both electron and hole distributions. Type-I and type-II hetero n-i-p-i structures are investigated. The in-plane dispersion relations and the effects of valence subband mixing on subband structures are also discussed.
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Acknowledgment - One of us (PPR) thanks Dr. M. K. Hibbs-Brenner of Honeywell for useful discussions. This work was supported in part by AFOSR/DARPA and Honeywell Inc.