Effect of superlattice structure on the thermoelectric figure of merit

Abstract

The electrical conductivity, the thermoelectric power, and the electrical contribution to the thermal conductivity of superlattices have been studied within the envelope-function approach for the electrons. The effects of tunneling through the barriers due to finite potential offsets and of the thermal currents through the barrier layers are shown to be essential to describe properly the thermoelectric figure of merit of realistic superlattices. The figure of merit is calculated as a function of superlattice period, potential barrier offset, and barrier width. It is found that the figure of merit has a maximum as a function of superlattice period and that its value there can be somewhat larger than that of the corresponding bulk. For larger periods the figure of merit is generally less than that of the correponding bulk.