Sistani M, Luong M A, den Hertog M I, Robin E, Spies M, Fernandez B, Yao J, Bertagnolli E, Lugstein A
Institute of Solid State Electronics, Technische Universität Wien , Gußhausstraße 25-25a , Vienna 1040 , Austria.
Université Grenoble Alpes, CEA, INAC, MEM , Grenoble F-38000 , France.
Nano Lett. 2018 Dec 12;18(12):7692-7697. doi: 10.1021/acs.nanolett.8b03366. Epub 2018 Nov 20.
The electrical and optical properties of low-dimensional nanostructures depend critically on size and geometry and may differ distinctly from those of their bulk counterparts. In particular, ultrathin semiconducting layers as well as nanowires have already proven the feasibility to realize and study quantum size effects enabling novel ultrascaled devices. Further, plasmonic metal nanostructures attracted recently a lot of attention because of appealing near-field-mediated enhancement effects. Thus, combining metal and semiconducting constituents in quasi one-dimensional heterostructures will pave the way for ultrascaled systems and high-performance devices with exceptional electrical, optical, and plasmonic functionality. This Letter reports on the sophisticated fabrication and structural properties of axial and radial Al-Ge and Al-Si nanowire heterostructures, synthesized by a thermally induced exchange reaction of single-crystalline Ge-Si core-shell nanowires and Al pads. This enables a self-aligned metallic contact formation to Ge segments beyond lithographic limitations as well as ultrathin semiconducting layers wrapped around monocrystalline Al core nanowires. High-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and μ-Raman measurements proved the composition and perfect crystallinity of these metal-semiconductor nanowire heterostructures. This exemplary selective replacement of Ge by Al represents a general approach for the elaboration of radial and axial metal-semiconductor heterostructures in various Ge-semiconductor heterostructures.
低维纳米结构的电学和光学性质严重依赖于尺寸和几何形状，可能与它们的体相材料有明显差异。特别是，超薄半导体层以及纳米线已经证明了实现和研究量子尺寸效应的可行性，这使得新型超大规模器件成为可能。此外，等离子体金属纳米结构由于其引人注目的近场介导增强效应，最近受到了广泛关注。因此，在准一维异质结构中结合金属和半导体成分将为具有卓越电学、光学和等离子体功能的超大规模系统和高性能器件铺平道路。本文报道了通过单晶Ge-Si核壳纳米线与Al焊盘的热诱导交换反应合成的轴向和径向Al-Ge及Al-Si纳米线异质结构的精密制造和结构特性。这使得能够在超越光刻限制的情况下与Ge段形成自对准金属接触，以及在单晶Al芯纳米线周围形成超薄半导体层。高分辨率透射电子显微镜、能量色散X射线光谱和μ拉曼测量证明了这些金属-半导体纳米线异质结构的组成和完美结晶度。Al对Ge的这种示例性选择性替代代表了在各种Ge-半导体异质结构中制备径向和轴向金属-半导体异质结构的通用方法。
