Invited Paper EM1+PV-TuM1
Enhancement of the Thermoelectric Figure of Merit in Bulk Semiconductors at the Atomic Level

Tuesday, November 10, 2009, 8:00 am, Room A8

Recently, several thermoelectric semiconductor systems have been developed with double the thermoelectric figure of merit, zT, of conventional materials. Almost all the progress comes from achieving reductions in thermal conductivity using nanotechnologies or structural disorder. Because the lattice thermal conductivity has a lower limit, the amorphous limit, further progress must come from an enhancement of the electrical properties, in particular the thermoelectric power or Seebeck coefficient. We present a new technique to achieve that, based on creating distortions of the density-of-states by doping with resonant impurities, resulting in a doubling of the zT of PbTe, a semiconductor used for power generation applications near 500 ^oC. We will also review current progress with this technique in Bi₂Te₃, the other classical thermoelectric, which we study because the commercial materials used for Peltier cooling are (Bi_1-xSb_x)₂(Te_1-ySe_y)₃ alloys. The theory behind this approach will be outlined, and its applicability to a wide variety of thermoelectric semiconductors discussed.