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Nano Research

Article Title

Self-organization of various “phase-separated” nanostructures in a single chemical vapor deposition

Authors

Jinmei Wang, Department of Physics, Indiana University, Bloomington, Indiana 47405, USA College of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
Dongyue Xie, Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
Zhen Li, Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
Xiaohang Zhang, Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
Xing Sun, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA
Amanda L. Coughlin, Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
Thomas Ruch, Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
Qiang Chen, Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
Yaroslav Losovyj, Department of Chemistry, Indiana University, Bloomington, Indiana 47408, USA
Seunghun Lee, Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
Heshan Yu, Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
Haidong Zhou, Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
Haiyan Wang, School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA
Jian Wang, Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
Shixiong Zhang, Department of Physics, Indiana University, Bloomington, Indiana 47405, USA Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA

Keywords

nanomaterials synthesis, silicon nanowires, topological crystalline insulators, phase separation, chemical vapor deposition

Abstract

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/SiOx core-shell nanowire heterostructures both with and without embedded manganese silicide particles, Mn11Si19 nanowires, and SnTe nanoplates. The Si/SiOx core-shell nanowires embedded with manganese silicide particles were grown along the 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 -oriented Si/SiOx core-shell nanowires and -oriented Mn11Si19 nanowires, 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.

Graphical Abstract

Publisher

Tsinghua University Press

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