ICT2014 Abstracts

The performance of a thermoelectric material is estimated via the relation of the Seebeck coefficient (S), electrical conductivity (σ) and thermal conductivity (κ) at a temperature (T), which is called the thermoelectric figure of merit, ZT=S²σT/κ. The achievement of a ZT above 1 is a historic mission assigned to the thermoelectric community. Research aimed at increasing ZT values in recent decades has been focused on the following three areas. First, the Seebeck coefficient can be increased through appropriate carrier doping or energy filtering of charge carriers. Second, lowering of the effective mass of the carriers and modulation doping in a quantum well can enhance the mobility (μ) of charge carriers. Third, thermal conductivity can be reduced by adding a number of interfaces and phonon scattering centers in a nanowire, nanotube, superlattice, alloy, or composite. To date, the majority of research has focused on increasing μ/κ. Heremans et al. emphasized the importance of the factor, S²n where n is a carrier density, on increasing ZT. They predicted that distortions of the electronic density of states (DOS) would induce a higher Seebeck coefficient in the thermoelectric semiconductor, resulting in an increased thermoelectric power factor (S²σ). Here, we report the thermoelectric power factors of 100 nm-thick, n-type, polycrystalline FeAs₂ film grown on Si(111) substrate.