Low-Contact-Resistance Graphene Devices with Nickel-Etched-Graphene Contacts

Abstract

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.

Formation and morphological evolution of self-similar 3D nanostructures on weakly interacting substrates

“…Such approaches may, for example, be relevant for achieving 2D metal film growth on 2D crystals, including graphene and Mo 2 S, and thereby synthesize low-resistivity electrical contacts on nanoelectronic devices [4,5,[7][8][9][10][11][12][13][14] or fabricate catalytic devices that exhibit enhanced turnover frequencies [6].…”

“…A notable example is the deposition of metal films on twodimensional (2D) crystals (e.g., graphene and MoS 2 ) [4][5][6] for which the tendency toward the formation of 3D agglomerates imposes technological obstacles for the use of 2D materials in a wide range of switching and, in some cases, catalytic devices [4][5][6][7][8][9][10][11][12][13][14]. Thus, understanding atomistic mechanisms that govern 3D island formation and shape evolution is a key step toward controlling film morphology and, by extension, the functionality of devices based on weakly interacting film/substrate materials systems.…”

Broadband 10 Gb/s operation of graphene electro‐absorption modulator on silicon

“…As the operation speed of the graphene modulator currently is limited by the RC delay, further design optimizations should focus on reducing device series resistance R s and capacitance C GOS . There are a lot of strategies to reduce R s : shrinking the distance between metal pad and waveguide (current value is 2 µm), increasing doping density in the slab area, increasing the thickness of the slab, improving the graphene quality and thus reduce the resistance contribution of the graphene sheet between metal pad and the GOS capacitor and using improved metal-graphene contact technologies [30]. Implementing these improvements, R s potentially can be reduced from the current value of 241 Ω to less than 50 Ω.…”

Defect-induced discriminative modulation of the highest occupied molecular orbital energies of graphene

“…Modulating such properties has been a focus of research towards the development of graphene-based devices. [10][11][12][13][14][15][16] Recently, defects have been introduced to control the mechanical, [17][18][19] electrical, [20][21][22][23][24][25] thermal, 26,27 magnetic, 28,29 and chemical 30 properties of graphene. For instance, molecular dynamics calculations have demonstrated Stone-Thrower-Wales defects' ability to modulate the mechanical properties of graphene sheets (GSs).…”