Use of quantum-well superlattices to obtain a high figure of merit from nonconventional thermoelectric materials

Abstract

Currently, the materials with the highest thermoelectric figure of merit (ZT) are one-band materials. The presence of both electrons and holes lowers ZT, so two-band materials such as semimetals are not useful thermoelectric materials. However, by preparing these materials in the form of two-dimensional quantum-well superlattices, it is possible to separate the two bands and transform the material to an effective one-carrier system. We have investigated theoretically the effect of such an approach and our results indicate that a significant increase in ZT may be achieved. This result allows the possibility of using a new class of materials as thermoelectric refrigeration elements.