Spacer strategy for exceptionally low thermal conductivity and high zT in antimony-doped bulk silicon

In this study, the effects of inserting mica into bulk silicon for thermoelectric use on the alloying, nanosize, and spacer effects that are mainly used to suppress thermal conductivity are examined. Results revealed that nanocrystallinity as well as the extremely high doping amount of antimony in the grains drastically enhance the power factor. Dislocations or vacancies can be induced at the nanoscopic level by performing multiple heat treatments and by inserting spacer materials at the bulk level, which in turn can inhibit the heat transport in high thermally conductive materials. Furthermore, a record and reliable figure-of-merit of ∼0.6 at 1173 K is obtained for mica-inserted SiSb _0.02 , in addition to reduced thermal conductivity (∼6.5 W/m-K). These observations open avenues for silicon and can further lead to the formation of intermetallic, half-Heusler, and other chalcogenide materials.