Thermoelectric power factor enhancement in metal/semiconductor nanocomposites by ionized nanoparticie scattering

摘要

We present a theoretical investigation of the thermoelectric power factor enhancement in metal/semiconductor nanocomposites by the energy dependent electron scattering from ionized nanoparticles. The metal nanoparticles embedded in semiconductors can be ionized to donate electrons to the matrix, which will result in a Coulomb potential tail around the nanoparticles. Here we show the significant effect of slowly varying potential tails on thermoelectric properties of the nanocomposites. The Coulomb potential is different from that of the conventional ionized impurities due to the finite size of the ionized particles, and the fact that the nanoparticles can give multiple electrons to the matrix. Detailed calculations for scattering rates and thermoelectric coefficients are presented for ErAs semi-metallic nanoparticles in inGaAs semiconductors. The partial wave method is used to consider the exact potential profile around nanoparticles and Boltzmann transport equation is used to calculate the transport coefficients. We find that an increase by 15~30% in power factor can be achieved over a wide temperature range in these material systems in addition to the thermal conductivity reduction to further enhance ZT.