title: Crystalline-Amorphous Silicon Nanocomposites with Reduced Thermal Conductivity for Bulk Thermoelectrics.
abstract: Responding to the need for thermoelectric materials with high efficiency in both conversion and cost, we developed a nanostructured bulk silicon thermoelectric materials by sintering silicon crystal quantum dots of several nanometers in diameters synthesized by plasma-enhanced chemical vapor deposition (PECVD). The material consists of hybrid structures of nanograins of crystalline silicon and amorphous silicon oxide. The percolated nanocrystalline region gives rise to high power factor with the high doping concentration realized by PECVD, and the binding amorphous region reduces thermal conductivity. Consequently, the nondimensional figure of merit reaches 0.39 at 600 °C, equivalent to the best reported value for silicon thermoelectrics. The thermal conductivity of the densely packed material is as low as 5 W m(-1) K(-1) in a wide temperature range from room temperature to 1000 °C, which is beneficial not only for the conversion efficiency but also for material cost by requiring less material to establish certain temperature gradient.
authors.affiliation: †Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Miura
authors.affiliation: ‡Department on Mechanical Sciences and Engineering Tokyo Institute of Technology, Tokyo 152-8550, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhou
authors.affiliation: ‡Department on Mechanical Sciences and Engineering Tokyo Institute of Technology, Tokyo 152-8550, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nozaki
authors.affiliation: †Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan.|§PRESTO, Japan Science and Technology Agency, 4-1-8, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Shiomi
keywords: nanostructure; plasma activated sintering; plasma-enhanced chemical vapor deposition; silicon; thermal conductivity; thermoelectric material