Tanusilp Sora-At, Sadayori Naoki, Kurosaki Ken
Graduate School of Engineering, Osaka University 2-1 Yamadaoka, Suita Osaka 565-0871 Japan.
Nitto Denko Corporation 1-1-2 Shimohozumi, Ibaraki Osaka 567-8680 Japan
RSC Adv. 2019 May 17;9(27):15496-15501. doi: 10.1039/c9ra02349f. eCollection 2019 May 14.
Nanostructured bulk silicon (bulk nano-Si) has attracted attention as an advanced thermoelectric (TE) material due to its abundance and low toxicity. However, oxidization will occur easily when bulk nano-Si is synthesized by a conventional method, which deteriorates the TE performance. Various methods to prevent such oxidation have been proposed but they need specific techniques and are thus expensive. Here, we propose a simple and cost-effective method named Surface Diffusion/Sintering Doping (SDSD) to synthesize bulk nano-Si for TEs. SDSD utilizes Si nanoparticles whose surface is coated with a native thin oxide layer. SDSD is composed of two steps, (1) a molecular precursor containing a doping element is added onto the oxide layer of Si nanoparticles and (2) the nanoparticles are sintered into a bulk state. During sintering, the doping element diffuses through the oxide layer forming conductive paths, which results in a high carrier concentration as well as high mobility. Furthermore, owing to the nanostructures, low lattice thermal conductivity ( ) is also achieved, which is an ideal situation for TEs. In this study, we show that P-doped bulk nano-Si synthesized by SDSD shows good TE performance due to its high carrier concentration, high carrier mobility, and low . Since SDSD takes advantage of oxidization, it is cost-effective and suitable for mass production to synthesize bulk nano-Si for TEs.
纳米结构块状硅（块状纳米硅）因其丰富性和低毒性而作为一种先进的热电（TE）材料受到关注。然而，当通过传统方法合成块状纳米硅时，很容易发生氧化，这会降低热电性能。已经提出了各种防止这种氧化的方法，但它们需要特定的技术，因此成本高昂。在此，我们提出一种名为表面扩散/烧结掺杂（SDSD）的简单且经济高效的方法来合成用于热电的块状纳米硅。SDSD利用表面涂有天然薄氧化层的硅纳米颗粒。SDSD由两个步骤组成，（1）将含有掺杂元素的分子前驱体添加到硅纳米颗粒的氧化层上，（2）将纳米颗粒烧结成块状。在烧结过程中，掺杂元素通过氧化层扩散形成导电路径，这导致高载流子浓度以及高迁移率。此外，由于纳米结构，还实现了低晶格热导率（ ），这对热电来说是理想的情况。在本研究中，我们表明通过SDSD合成的P掺杂块状纳米硅由于其高载流子浓度、高载流子迁移率和低 而表现出良好的热电性能。由于SDSD利用了氧化作用，它具有成本效益且适合大规模生产用于热电的块状纳米硅。
