Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, USA.
Chem Soc Rev. 2018 May 8;47(9):3037-3058. doi: 10.1039/c7cs00828g.
Over the past decade, the field of two-dimensional (2D) layered materials has surged, promising a new platform for studying diverse physical phenomena that are scientifically intriguing and technologically relevant. Contacts are the communication links between these 2D materials and the three-dimensional world for probing and harnessing their exquisite electronic properties. However, fundamental challenges related to contacts often limit the ultimate performance and potential of 2D materials and devices. This article provides a comprehensive overview of the basic understanding and importance of contacts to 2D materials and various strategies for engineering and improving them. In particular, we elucidate the phenomenon of Fermi level pinning at the metal/2D contact interface, the Schottky versus Ohmic nature of the contacts and various contact engineering approaches including interlayer contacts, phase engineered contacts, and basal versus edge plane contacts, among others. Finally, we also discuss some of the relatively under-addressed and unresolved issues, such as contact scaling, and conclude with a future outlook.
在过去的十年中，二维（2D）层状材料领域迅速发展，为研究各种具有科学趣味性和技术相关性的物理现象提供了新的平台。接触是这些 2D 材料与三维世界进行沟通的联系，用于探测和利用它们精致的电子特性。然而，与接触相关的基本挑战常常限制了 2D 材料和器件的最终性能和潜力。本文全面概述了接触对于 2D 材料的基本理解和重要性，以及各种用于工程设计和改进接触的策略。特别是，我们阐明了金属/2D 接触界面处费米能级钉扎的现象、接触的肖特基与欧姆性质，以及各种接触工程方法，包括层间接触、相工程接触、基面与边缘面接触等。最后，我们还讨论了一些相对较少被关注和尚未解决的问题，例如接触缩小问题，并对未来的发展进行了展望。
