We discuss the unusual electronic properties of n-i-p-i doping superlattices, i.e. semiconductors modulated by periodically alternating n- and p- doping. The work on these systems involving GaAs as a host material is briefly reviewed. New features which are to be expected from doping superlattices using IV-VI semiconductors as host materials are then presented. It is shown that the different electronic structure of these materials leads to doping superlattice properties which are qualitatively different from those observed in III-V materials. The effect of a magnetic field on the electronic states is also discussed. Finally we propose a new hetero n-i-p-i superlattice which combines the tunability of doping superlattices with the absence of impurity scattering of modulation doped hetero superlattices and allows for the observation of the subband structure in luminescence experiments.