Dipartimento di Ingegneria dell'Informazione, Università di Pisa Via G. Caruso 16, 56122, Pisa, Italy.
University of Siegen, Hölderlinstrasse 3, 57076, Siegen, Germany.
Sci Rep. 2017 Jul 11;7(1):5109. doi: 10.1038/s41598-017-05069-7.
The performance of devices and systems based on two-dimensional material systems depends critically on the quality of the contacts between 2D material and metal. A low contact resistance is an imperative requirement to consider graphene as a candidate material for electronic and optoelectronic devices. Unfortunately, measurements of contact resistance in the literature do not provide a consistent picture, due to limitations of current graphene technology, and to incomplete understanding of influencing factors. Here we show that the contact resistance is intrinsically dependent on graphene sheet resistance and on the chemistry of the graphene-metal interface. We present a physical model of the contacts based on ab-initio simulations and extensive experiments carried out on a large variety of samples with different graphene-metal contacts. Our model explains the spread in experimental results as due to uncontrolled graphene doping and suggests ways to engineer contact resistance. We also predict an achievable contact resistance of 30 Ω·μm for nickel electrodes, extremely promising for applications.
基于二维材料系统的器件和系统的性能，关键取决于 2D 材料与金属之间接触的质量。低接触电阻是将石墨烯视为电子和光电设备候选材料的必要条件。不幸的是，由于当前石墨烯技术的限制以及对影响因素的不完全了解，文献中接触电阻的测量并未提供一致的结果。在这里，我们表明接触电阻本质上取决于石墨烯的片电阻和石墨烯-金属界面的化学性质。我们提出了一种基于从头算模拟和在具有不同石墨烯-金属接触的各种样品上进行的广泛实验的接触模型。我们的模型解释了实验结果的分散，这是由于石墨烯掺杂不受控制造成的，并提出了控制接触电阻的方法。我们还预测镍电极的接触电阻可达 30 Ω·μm，这对于应用来说非常有前景。
