使用精确旋转对齐来制造范德瓦尔斯异构结构
Summary
在本作品中,我们描述了一种技术,该技术用于通过堆叠超薄分层 2D 材料来创建新晶体(范德瓦尔异构结构),并精确控制位置和相对方向。
Abstract
在本作品中,我们描述了一种通过堆叠不同的超薄分层 2D 材料来创建新晶体(范德瓦尔斯异构结构)的技术。我们不仅演示横向控制,而且重要的是,还要控制相邻图层的角对齐。该技术的核心由自建传输设置表示,该装置允许用户控制传输中涉及的各个晶体的位置。这是通过亚微米(平移)和亚度(角)精度实现的。在将它们堆叠在一起之前,隔离晶体由由编程软件接口控制的定制设计移动阶段单独操作。此外,由于整个传输设置由计算机控制,用户可以远程创建精确的异质结构,而无需直接接触传输设置,将该技术标记为”免提”。除了介绍传输设置外,我们还介绍了两种用于制备随后堆叠的晶体的技术。
Introduction
在新兴的二维(2D)材料领域,研究人员开发了一种技术,使石墨烯1,2,3(原子扁平的碳原子片)从分离后开始。石墨。石墨烯是更大等级的分层二维材料的成员,也称为范德瓦尔斯材料或晶体。它们具有强共价层内粘结和弱范德瓦尔斯层间耦合。因此,从石墨中分离石墨烯的技术也可以应用于其他二维材料,其中可以打破弱层间粘结并隔离单层。该领域的一个关键发展是证明,正如范德瓦尔斯债券持有相邻的层二维材料可以打破,他们也可以放回一起2,4。因此,通过控制地堆叠具有不同属性的 2D 材料层,可以创建 2D 材质的晶体。这激起了极大的兴趣,因为以前在自然界中不存在的材料可以创造,目的是发现以前无法进入的物理现象4,5,6,7 、8、9或为技术应用开发高级设备。因此,对堆叠2D材料进行精确控制已成为10、11、12研究领域的主要目标之一。
特别是范德瓦尔斯异质结构中相邻层之间的扭曲角是控制材料特性的重要参数13。例如,在某些角度上,相邻图层之间引入相对扭曲可以有效地以电子方式使两个图层分离。这在石墨烯14,15以及过渡金属三卤基尼16,17,18,19中进行了研究。最近,令人惊讶的是,它也可以改变这些材料的物质状态。在低温下,以”神奇角度”定向的双层石墨烯在低温下充当Mott绝缘体,在电子密度适当调谐时,甚至超导体,这一发现引起了极大的兴趣,并认识到了角控制的重要性。当制造分层范德瓦尔斯异质结构13,20,21。
在通过调整层之间的相对方向来调整新型范德瓦尔材料特性的想法所开辟的科学机会的激励下,我们提出了一种自制仪器以及创建这种结构的程序与角控制。
Protocol
1. 传输程序的仪器 为了可视化传输过程,使用可在明场照明下操作的光学显微镜。由于 2D 晶体的典型尺寸为 1~500 μm2,因此显微镜配有 5 倍、50 倍和 100 倍的长工作距离目标。显微镜还必须配备连接到计算机的照相机 (图 1a)。 使用单独的操纵器单独控制两个即将堆叠的晶体的位置。采用计算机可编程和控制的操纵器,以尽量减少传输过程中的振动。注:…
Representative Results
为了说明我们程序的结果和有效性,我们提出了一系列角度控制的二硫二铵(ReS2)薄晶体。为了强调所述方法也可以应用于原子薄层,我们还举例说明了两个相对扭曲的单层二氧化硫(MoS2)的构造。 为了演示传输设置的角度对齐功能,我们使用二硫化硫二铵 (ReS2)。由于其平面内各向异性晶格结构,这种晶体机械…
Discussion
此处介绍的自建传输设置提供了一种使用横向和旋转控制构建新型分层材料的方法。与文献10、25中描述的其他解决方案相比,我们的系统不需要复杂的基础设施,但它达到了2D晶体受控对齐的目标。
该步骤中最关键的步骤是将顶部晶体与底部晶体对齐并放置。振动可能是对齐失败的原因,因此,必须尽量减少其影响。在这方面,此处介绍?…
Divulgaciones
The authors have nothing to disclose.
Acknowledgements
作者承认渥太华大学和NSERC发现资助RGPIN-2016-06717和NSERCSPG QC2DM的资助。
Materials
| 5X objective lens | Nikon Metrology | MUE12050 | 23.5 mm working distance and 0.15 numerical aperture |
| 50X objective lens | Nikon Metrology | MUE21500 | 19 mm working distance and 0.4 numerical aperture |
| 100X objective lens | Nikon Metrology | MUE21900 | 4.5 mm working distance and 0.8 numerical aperture |
| Acetone | Sigma-Aldrich | 270725 | Purity ≥99.90% |
| Adhesive tape | Ultron Systems, Inc. | ||
| Anisole | MicroChem | ||
| Atomic force microscope | Bruker | Dimension Icon | We typicall use the ScanAsyst mode |
| Bottom stage rotation manipulator | Zaber Technologies | X-RSW60A-PTB2 | 360° travel with step size of 4.091 μrad |
| Bottom stage X manipulator | Zaber Technologies | X-LSM025A-PTB2 | 25 mm travel with step size of 47.625 nm |
| Bottom stage Y manipulator | Zaber Technologies | X-LSM025A-PTB2 | 25 mm travel with step size of 47.625 nm |
| Bottom stage Z manipulator | Zaber Technologies | X-VSR40A-KX14A | 40 mm travel with step size of 95.25 nm |
| Isopropanol | Sigma-Aldrich | 563935 | Purity 99.999% |
| LabVIEW software | National Instruments | ||
| Macor | McMaster-Carr | 8489K238 | |
| Microscope camera | Zeiss | 426555-0000-000 | 5 megapixel, 47 fps live frame rate, exposure time of 100 μs – 2 s, color camera |
| Molybdenum disulfide (MoS2) | HQ Graphene | ||
| Optical breadboard | Thorlabs, Inc. | MB4545/M | |
| Optical microscope | Nikon Metrology | LV150N | |
| Oxygen plasma etcher | Plasma Etch, Inc. | PE-50 | |
| PDMS stamp | Gel-Pak | PF-20-X4 | |
| PMMA 950 A6 | MichroChem Corp. | M230006 0500L1GL | |
| Polypropylene carbonate | Sigma-Aldrich | 389021-100g | |
| PVA Partall #10 | Composites Canada | ||
| Rhenium disulfide (ReS2) | HQ Graphene | ||
| Si/SiO2 substrate | Nova Electronics Materials | HS39626-OX | |
| Spin coater | Laurell Technologies | WS-650-23 | |
| Temperature controller | Auber Instruments | SYL-23X2-24 | Controls the temperature of the bottom stage via a J type thermocouple |
| Top stage controller unit | Mechonics | CF.030.0003 | |
| Top stage X manipulator | Mechonics | MS.030.1800 | 18 mm travel with step size of 11 nm |
| Top stage Y manipulator | Mechonics | MS.030.1800 | 18 mm travel with step size of 11 nm |
| Top stage Z manipulator | Mechonics | MS.030.3000 | 30 mm travel with step size of 11 nm |
| Ultrasonic bath | Elma Schmidbauer GmbH | Elmasonic P 30 H |
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Citar este artículo
Boddison-Chouinard, J., Plumadore, R., Luican-Mayer, A. Fabricating van der Waals Heterostructures with Precise Rotational Alignment. J. Vis. Exp. (149), e59727, doi:10.3791/59727 (2019).