High Performance Multi Barrier Thermionic Devices

摘要

Thermoelectric transport perpendicular to layers in multiple barrier superlattice structures is investigated theoretically in two limiting cases of no lateral momentum scattering and strong scattering. In the latter regime when lateral momentum is not conserved, the number of electrons participating in thermionic emission will dramatically increase. The cooling power density is calculated using Fermi-Dirac statistics, density-of-states for a finite quantum well and the quantum mechanical transmission coefficient in the superlattice. Calculation results show that metallic based superlattices with tall barriers (>10 eV) can achieve a large power factor on the order of 0.06W/mK squared with a moderate electronic contribution to thermal conductivity of 1.8W/mK. If the lattice contribution to thermal conductivity is on the order of 1W/mK, ZT values higher than 5 can be achieved at room temperature.