Thermoelectric properties of SiGe sintered alloys with modified grain boundaries

Modification of grain boundaries of SiGe sintered alloys has been investigated to improve their thermoelectric figure-of-merit using the potential barrier scattering. We attempted to prepare p-SiGe:B/i-Ge composite sintered alloys, where grains of p-type SiGe doped with boron were surrounded with thin grain-boundary layers of intrinsic (undoped) Ge. This heterostructured composite alloys seem to have a potential barrier for holes at the grain boundaries. The obtained SiGe/Ge sintered alloys have a larger Seebeck coefficient than SiGe alloys. It seems that this difference of the Seebeck coefficient is due to the potential barrier scattering at the grain boundary.