Electrical conductivity of δ doping superlattices parallel to the growth direction

The electrical conductivity σ has been calculated for n-type δ doping GaAs superlattices (SLs) in a direction perpendicular to the layers. The transport along the SL growth direction is investigated by first performing self-consistent calculations of the miniband structure as a function of the SLsʹ periods d and the sheet doping concentrations ND. The Schrödinger equation, with the appropriate periodic boundary condition, coupled to the Poisson equation are self-consistently solved within the framework of the local density functional approximation for the electron exchange-correlation effects. Assuming that the transport in the SL occurs through extended miniband states, σ is calculated at zero temperature and low field ohmic limits by the quasi-classical Boltzmann kinetic equation. Using semiquantitative arguments we have shown recently that the particular miniband structure of the δ doping SLs leads to a plateau-like behaviour of σ as a function of the Fermi level position or of the donor concentration. In the present work numerical values of σ are presented.