Modeling and characterization of thermoelectric properties of SiGe nanocomposites

[摘要] (cont.) Grain boundaries in nanocomposites can scatter phonons, when their mean free paths are longer than the grain size. Mean free paths of electrons are usually shorter than the grain size of nanocomposites, so that the electrical conductivities of nanocomposites are not expected to change significantly. However, the experimental results show that nanostructures indeed affect electron transport. The grain boundary effects on electron transport are investigated to explain the experiments. Furthermore, the effects of nanosized pores are explored. Our experimental results show that pores in nanocomposites degrade the electrical conductivity more than predicted by effective medium theories. A scattering model is developed to understand the transport phenomena in porous materials. These modeling studies can also be used to guide sample preparation conditions.

[发布机构] Massachusetts Institute of Technology