Characterization of p-type PbEuTe/PbTe MQW structures with high thermoelectric figures of merit in the PbTe quantum wells

Abstract

A large enhancement in the Seebeck coefficient, thermoelectric power factor and figure of merit (Z/sub 2D/T) is reported in very high carrier concentration p-type PbTe quantum wells grown by molecular beam epitaxy. The estimated Z/sub 2D/T (using accepted bulk values for lattice thermal conductivity) is as high as 1.5 at 300 K. Power factor values up to 160 /sub /spl mu//Wcm/sup -1/K/sup -2/ were measured at 300 K, indicating a power factor in p-type quantum wells that is approximately five times the best bulk or homogeneous p-type value. Thinner barriers yielded lower thermoelectric power factors and figures of merit. The high power factor was achieved with a barrier thickness less than half that previously used to demonstrate enhanced thermoelectric power factors in n-type quantum wells. X-ray diffraction/reflection characterization results of the multiple-quantum-well (MQW) structures at both low and high Bragg angles yield precise values for the MQW periodicity.