Self-organization of various “phase-separated” nanostructures in a single chemical vapor deposition
Self-organization of various “phase-separated” nanostructures in a single chemical vapor deposition
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DOI：
10.1007/s12274-020-2798-5
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发表时间：
2020-05
期刊：
影响因子：
9.9
通讯作者：
Jin-mei Wang;D. Xie;Zhen Li;Xiaohang Zhang;Xing Sun;Amanda L. Coughlin;T. Ruch;Qiang Chen;Y. Losovyj;Seunghun Lee;Heshan Yu;Haidong Zhou;Haiyan Wang;Jian Wang;Shixiong Zhang
中科院分区：
文献类型：
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作者：
Jin-mei Wang;D. Xie;Zhen Li;Xiaohang Zhang;Xing Sun;Amanda L. Coughlin;T. Ruch;Qiang Chen;Y. Losovyj;Seunghun Lee;Heshan Yu;Haidong Zhou;Haiyan Wang;Jian Wang;Shixiong Zhang
化学气相沉积（CVD）是可控合成功能纳米材料的最通用技术之一。当诱导多个前体时，CVD过程通常引起掺杂或合金化合物的生长。在这项工作中，我们展示了自组装的各种“相分离”的功能性纳米结构从一个单一的CVD在各种前体的存在下。具体而言，以硅为衬底，Mn和SnTe粉末为前驱体，我们获得了自组织纳米结构，包括Si/SiOx核-壳纳米线异质结构（含和不含嵌入的硅化锰颗粒）、Mn 11 Si 19纳米线和SnTe纳米片。通过Au催化的气-液-固工艺，在Si/SiOx核-壳纳米线上沿着晶化Si方向生长锰硅化物颗粒<111>，其中Si和Mn蒸气分别来自加热的硅衬底和Mn粉末。相反，直接气相-固相沉积导致无颗粒<110>取向的Si/SiOx核壳纳米线和<100>取向的Mn 11 Si 19纳米线，这是一种很有前途的热电材料。在这些纳米结构中没有检测到Sn或Te杂质，直到实验极限。拓扑晶体绝缘体SnTe纳米片与占主导地位的{100}和{111}方面被发现是免费的Mn（和Si）杂质，虽然纳米粒子和纳米线含有Mn的纳米片附近发现。虽然在SnTe纳米片中观察到多通道传输，但它可能与由于表面氧化引起的拓扑表面状态无关。最后，我们进行了热力学分析和密度泛函理论计算，以了解“相分离”的现象，并进一步讨论了一般的方法来生长相纯的样品时，前体含有残留的杂质。
Chemical vapor deposition (CVD) is one of the most versatile techniques for the controlled synthesis of functional nanomaterials. When multiple precursors are induced, the CVD process often gives rise to the growth of doped or alloy compounds. In this work, we demonstrate the self-assembly of a variety of ‘phase-separated’ functional nanostructures from a single CVD in the presence of various precursors. In specific, with silicon substrate and powder of Mn and SnTe as precursors, we achieved self-organized nanostructures including Si/SiOxcore-shell nanowire heterostructures both with and without embedded manganese silicide particles, Mn11Si19nanowires, and SnTe nanoplates. The Si/SiOxcore-shell nanowires embedded with manganese silicide particles were grown along the <111> direction of the crystalline Si via an Au-catalyzed vapor-liquid-solid process, in which the Si and Mn vapors were supplied from the heated silicon substrates and Mn powder, respectively. In contrast, direct vapor-solid deposition led to particle-free <110>-oriented Si/SiOxcore-shell nanowires and <100>-oriented Mn11Si19nanowires, a promising thermoelectric material. No Sn or Te impurities were detected in these nanostructures down to the experimental limit. Topological crystalline insulator SnTe nanoplates with dominant {100} and {111} facets were found to be free of Mn (and Si) impurities, although nanoparticles and nanowires containing Mn were found in the vicinity of the nanoplates. While multiple-channel transport was observed in the SnTe nanoplates, it may not be related to the topological surface states due to surface oxidation. Finally, we carried out thermodynamic analysis and density functional theory calculations to understand the ‘phase-separation’ phenomenon and further discuss general approaches to grow phase-pure samples when the precursors contain residual impurities.