HgCdTe superlattices for solid-state cryogenic refrigeration

Abstract

A tall barrier superlattice structure based on mercury cadmium telluride material system is proposed that can achieve a large effective thermoelectric figure of merit (ZTmax∼3) at cryogenic temperatures. Calculations based on the Boltzmann transport equation taking into account the quantum mechanical electron transmission show that the Seebeck coefficient can be increased significantly at low temperatures with the use of nonplanar barriers as the thermal spreading of the electron density is tightened around the Fermi level. This provides a better asymmetric differential conductivity around the Fermi level close to the top of the barrier. Consequently, a high thermoelectric power factor is produced resulting in a large ZT.