High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
Nanoscale. 2017 Jul 13;9(27):9520-9528. doi: 10.1039/c7nr02502e.
The metal-graphene contact resistance has been identified to be a key bottleneck for achieving high performance of graphene transistors. It is crucial to understand the electrical properties of graphene and the carrier transport mechanism under the contact metal. Here, we have developed a new method of characterizing the electrical properties of graphene under the metal contact. It was found that the electrical properties of graphene under the metal can be tuned via the back-gate voltage and display ambipolar behavior. A quantum tunneling model for graphene-metal physical contact has been proposed. The probability of electric field-tunable tunneling has been derived from the results of measurements for the first time. The model predicts that even for physical contact the contact resistance can be much lower than 100 Ω μm when graphene is more heavily doped and the interfacial layer is eliminated. This study paves the way to achieving ultralow graphene-metal contact resistance in graphene devices for terahertz applications.
金属-石墨烯接触电阻被确定为实现石墨烯晶体管高性能的关键瓶颈。了解石墨烯的电学性质以及在接触金属下的载流子输运机制至关重要。在这里，我们开发了一种新的方法来表征金属接触下的石墨烯的电学性质。结果发现，通过背栅电压可以调节金属下石墨烯的电学性质，并显示出双极性行为。提出了一种用于石墨烯-金属物理接触的量子隧穿模型。首次从测量结果中推导出电场可调谐隧穿的概率。该模型预测，即使对于物理接触，当石墨烯掺杂更重且消除界面层时，接触电阻也可以远低于 100 Ωμm。这项研究为在太赫兹应用中实现石墨烯器件中超低的石墨烯-金属接触电阻铺平了道路。
