Enhancement of Thermoelectric Properties by Modulation-Doping in Silicon Germanium Alloy Nanocomposites

Modulation-doping was theoretically proposed and experimentally proved to be effective in increasing the power factor of nanocomposites (Si[subscript 80]Ge[subscript 20])[subscript 70](Si[subscript 100]B[subscript 5])[subscript 30] by increasing the carrier mobility but not the figure-of-merit (ZT) due to the increased thermal conductivity. Here we report an alternative materials design, using alloy Si[subscript 70]Ge[subscript 30] instead of Si as the nanoparticles and Si[subscript 95]Ge[subscript 5] as the matrix, to increase the power factor but not the thermal conductivity, leading to a ZT of 1.3 ± 0.1 at 900 °C.Solid-State Solar-Thermal Energy Conversion Center (funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001299/DE-FG02-09ER46577