Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117583.
ACS Nano. 2014 Jan 28;8(1):994-1001. doi: 10.1021/nn405834b. Epub 2013 Dec 19.
The performance of graphene-based transistors is often limited by the large electrical resistance across the metal-graphene contact. We report an approach to achieve ultralow resistance metal contacts to graphene transistors. Through a process of metal-catalyzed etching in hydrogen, multiple nanosized pits with zigzag edges are created in the graphene portions under source/drain metal contacts while the graphene channel remains intact. The porous graphene source/drain portions with pure zigzag-termination form strong chemical bonds with the deposited nickel metallization without the need for further annealing. This facile contact treatment prior to electrode metallization results in contact resistance as low as 100 Ω·μm in single-layer graphene field-effect transistors, and 11 Ω·μm in bilayer graphene transistors. Besides 96% reduction in contact resistance, the contact-treated graphene transistors exhibit 1.5-fold improvement in mobility. More importantly, the metal-catalyzed etching contact treatment is compatible with complementary metal-oxide-semiconductor (CMOS) fabrication processes, and holds great promise to meet the contact performance required for the integration of graphene in future integrated circuits.
石墨烯基晶体管的性能通常受到金属-石墨烯接触处的大电阻的限制。我们报告了一种实现超低电阻金属接触石墨烯晶体管的方法。通过在氢气中进行金属催化蚀刻的过程，在源/漏金属接触下的石墨烯部分中创建了多个具有锯齿边缘的纳米级凹坑，而石墨烯沟道保持完整。具有纯锯齿端的多孔石墨烯源/漏部分与沉积的镍金属化之间形成强化学键，而无需进一步退火。在电极金属化之前进行这种简单的接触处理，可使单层石墨烯场效应晶体管的接触电阻低至 100 Ω·μm，双层石墨烯晶体管的接触电阻低至 11 Ω·μm。除了接触电阻降低 96%之外，经过接触处理的石墨烯晶体管的迁移率提高了 1.5 倍。更重要的是，金属催化蚀刻接触处理与互补金属氧化物半导体 (CMOS) 制造工艺兼容，有望满足未来集成电路中石墨烯集成所需的接触性能。
