Superlattice applications to thermoelectricity

We present a theoretical framework for estimating the effects of a superlattice (SL) on the thermoelectric (TE) transport in semiconductors. We consider both transverse and parallel conduction through the SL, and in the latter case, the possibility of modulation doping. Our calculations of electron and phonon transport are based on a two-band single-valley model for heavily doped n-type Si80Ge20, with modifications to account for the effects of parallel and transverse transport through a SL. For parallel transport, we find modest improvement in the TE figure-of-merit, only for the narrowest SL (5.4 Å). For transverse conduction, we find that if the SL can be designed to inhibit the conduction of low-energy carriers, then large improvements in the TE figure-of-merit are possible, as large as +100% over the bulk.