Record low metal — (CVD) graphene contact resistance using atomic orbital overlap engineering

Meersha, Adil; Variar, Harsha B.; Bhardwaj, Kirti; Mishra, Abhishek; Raghavan, Srinivasan; Bhat, Navakanta; Shrivastava, Mayank

doi:10.1109/iedm.2016.7838352

Cited by 27 publications

(20 citation statements)

References 11 publications

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“…In this work, we investigate systematically the influence of size and density of round holes in graphene under Au contact metal, and the influence of the resulting hole‐to‐graphene ratio. In contrast to previous studies, where understanding of the trade‐off between the beneficial role of the edge contacts and the prejudicial impact of the etched graphene was limited to a qualitative perspective, we provide deeper insights into optimal contact configurations studying patterns of holes with varying diameter down to 50 nm. In addition, we analyze the impact of a varying charge carrier concentration in the graphene under the contact and rationalize the phenomenon of improvement in current injection associated with patterning by first‐principles‐based simulations.…”

Section: Introductionmentioning

confidence: 92%

Ultralow Specific Contact Resistivity in Metal–Graphene Junctions via Contact Engineering

Passi

Gahoi

Marín

et al. 2018

Adv Materials Inter

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A systematic investigation of graphene edge contacts is provided. Intentionally patterning monolayer graphene at the contact region creates well-defined edge contacts that lead to a 67% enhancement in current injection from a gold contact. Specific contact resistivity is reduced from 1372 Ωµm for a device with surface contacts to 456 Ωµm when contacts are patterned with holes. Electrostatic doping of the graphene further reduces contact resistivity from 519 Ωµm to 45 Ωµm, a substantial decrease of 91%. The experimental results are supported and understood via a multi-scale numerical model, based on density-functional-theory calculations and transport simulations. The data is analyzed with regards to the edge perimeter and hole-to-graphene ratio, which provides insights into optimized contact geometries. The current work thus indicates a reliable and reproducible approach for fabricating low resistance contacts in graphene devices.We provide a simple guideline for contact design that can be exploited to guide graphene and 2D material contact engineering.The extraordinary electronic, optoelectronic and mechanical properties of graphene make it a promising candidate as a technology booster for micro-and nanoelectronics applications.Examples include radio frequency electronics, 1,2 integrated photodetectors, 3-5 and nanoelectromechanical systems. 6,7 One of the major bottlenecks limiting the performance of graphene-based devices is the large and varying value of specific contact resistivity (R C ) between metal contact electrodes and graphene. [8][9][10][11] When a metal is brought into contact with graphene, a junction with high contact resistivity is created, typically attributed to the low density of states (DOS) in graphene in particular when the Fermi level is near the Dirac point. 11 Although abinitio calculations provide deeper insights into the contact problem, they also highlight the importance of the metal. 12-14 Experimentally, various methods have been reported to reduce R C : one of the most common approaches is post-metallization annealing. [15][16][17] Other methods aim to modify the graphene prior to metallization in a random manner, such as low power oxygen plasma etch (with or without post-metallization annealing), 18 ozone pre-treatment, 19 intentional doping of graphene below the contact metal, 20 and ion beam irradiation. 21,22 A more deterministic approach is the formation of "edge"-contacts, where the graphene under the contact is partially removed by lithographic methods to enable the formation of covalent bonds between graphene and metal. This idea was proposed by means of an ingenious contact geometry by Wang 23 . Subsequently, the partial removal of the graphene under the contact by lithography, plasma or ion bombardment allowed a more versatile contact design. In particular, Smith et al. 24 investigated edge patterning of graphene with rectangular cuts under palladium (Pd) and copper (Cu) contacts with the transfer length method (TLM). The conclusion of this study was extended by Park et a...

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Section: Introductionmentioning

confidence: 92%

Ultralow Specific Contact Resistivity in Metal–Graphene Junctions via Contact Engineering

Passi

Gahoi

Marín

et al. 2018

Adv Materials Inter

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“…[5][6][7][8] After more than a decade of studies, contact resistance is still now regarded as one of the bottlenecks for realizing high-performance GFETs: [5][6][7][8] although ultra-low contact resistance (< 100 Ω·µm) has been achieved by top-and edge-contact strategies (see Figure 1a), it is mostly limited within a small area so far, with the contact pattern necessarily defined by either electron-beam lithography (EBL) or delicate ozone/ion beam treatment for a clean contact interface (see Table S1). [9][10][11][12][13][14][15][16] Such bottlenecks have to be overcome in order to achieve large scale processing, productization and further applications of high-performance GFETs.…”

Section: The Majority Of the Fabricated Devices Show Contact Resistanmentioning

confidence: 99%

“…By contrast, in Ref 18 , a much increased contact height of 100 nm was used, but the contact length was fixed at 10 µm and the effect of varying this latter parameter was not investigated. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 11,12,15,26,36 blue squares, data from refs; 14,16 red triangles, data from refs; 6,7,9,10,28,37 red circles, data from ref; 27 green circles, data from refs; 8,18,23 earthy yellow diamond, data from ref. 26 In this work, we systematically explored the influence of the contact geometry in a bottom contact device by adjusting the contact height and length (denoted as ConH and ConL, referring to the height and the length of the contact electrodes) between 1.8 nm-80 nm and 10 µm-30 µm, respectively.…”

Section: Electrical Characterization Of Vdw Contacted Gfet On Rigid Smentioning

confidence: 99%

van der Waals Contact Engineering of Graphene Field-Effect Transistors for Large-Area Flexible Electronics

et al. 2019

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“…For instance, R C largely degrades the output conductance and the maximum oscillation frequency of graphene-FETs (GFETs) [1], [3]. Thus, to boost the graphene technology, design strategies to optimize R C are urgently required to make graphene a viable solution for high performance electronic devices [4].…”

Section: Introductionmentioning

confidence: 99%

DFT study of graphene doping due to metal contacts

Khakbaz

Driussi

Gambi

et al. 2019

2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)

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The experimental results of Metal-graphene (M-G) contact resistance (RC) have been investigated in-depth by means of Density Functional Theory (DFT). The simulations allowed us to build a consistent picture explaining the RC dependence on the metal contact materials employed in this work and on the applied back-gate voltage. In this respect, the M-G distance is paramount in determining the RC behavior.

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Record low metal — (CVD) graphene contact resistance using atomic orbital overlap engineering

Cited by 27 publications

References 11 publications

Ultralow Specific Contact Resistivity in Metal–Graphene Junctions via Contact Engineering

Ultralow Specific Contact Resistivity in Metal–Graphene Junctions via Contact Engineering

van der Waals Contact Engineering of Graphene Field-Effect Transistors for Large-Area Flexible Electronics

DFT study of graphene doping due to metal contacts

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