We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

Physical Review B

where A represents the magnetic vector potential, is an integral of the hydromagnetic equations. This -integral made it possible to formulate a variational principle for the force-free magnetic fields. The integral expresses the fact that motions cannot transform a given field in an entirely arbitrary different field, if the conductivity of the medium isconsidered infinite. In this paper we shall show that the full set of hydromagnetic equations admit five more integrals, besides the energy integral, if dissipative processes are absent. These integrals, as we shall presently verify, are I2 =fbHvdV, (2)

Proceedings of the National Academy of Sciences

Graphene, a single layer of carbon atoms in a honeycomb lattice, offers a number of fundamentally superior qualities that make it a promising material for a wide range of applications, particularly in electronic devices. Its unique form factor and exceptional physical properties have the potential to enable an entirely new generation of technologies beyond the limits of conventional materials. The extraordinarily high carrier mobility and saturation velocity can enable a fast switching speed for radio-frequency analog circuits. Unadulterated graphene is a semi-metal, incapable of a true off-state, which typically precludes its applications in digital logic electronics without bandgap engineering. The versatility of graphene-based devices goes beyond conventional transistor circuits and includes flexible and transparent electronics, optoelectronics, sensors, electromechanical systems, and energy technologies. Many challenges remain before this relatively new material becomes commercially viable, but laboratory prototypes have already shown the numerous advantages and novel functionality that graphene provides.

Graphene: An Emerging Electronic Material

Graphene is a relatively new material with unique properties that holds promise for electronic applications. Since 2004, when the first graphene samples were intentionally fabricated, the worldwide research activities on graphene have literally exploded. Apart from physicists, also device engineers became interested in the new material and soon the prospects of graphene in electronics have been considered. For the most part, the early discussions on the potential of graphene had a prevailing positive mood, mainly based on the high carrier mobilities observed in this material. This has repeatedly led to very optimistic assessments of the potential of graphene transistors and to an underestimation of their problems. In this paper, we discuss the properties of graphene relevant for electronic applications, examine its advantages and problems, and summarize the state of the art of graphene transistors.

Graphene Transistors: Status, Prospects, and Problems

Impedance spectroscopy and equivalent circuits of conductively doped organic hole-transport materials

The parasitic resistance of different source/drain metals for top-gated graphene field-effect transistors was extracted by fitting the measured ID-VG data with a resistance model and was found to be a significant part of the total resistance of graphene field-effect transistors. The results show that Ti/Au gives relatively large contact resistance, about 7500 Ω·μm. Ni/Au contact shows better result compared to Ti/Au, which is around 2100 Ω·μm. The lowest contact resistance was given by Ti/Pd/Au, which is around 750 Ω·μm. The contact resistivity for Ti/Pd/Au source/drain contact is around 2 × 10−6 Ω·cm2, close to state of the art GaAs technology.

Contact resistance in top-gated graphene field-effect transistors

We present an approach to mass produce high-quality graphene on insulator substrate. Ni dots with single or few grains were achieved by annealing. Electron backscattered diffraction indicated that almost all of the Ni dots had (111) surface that is parallel to the substrate. Single-layer graphene with good crystalline quality has been grown on Ni dots. The patterned graphene films were transferred to insulating substrates by wafer bonding and etch back technique, which resulted in zero misalignment, low contamination, and high yield (>90%). Graphene-based field-effect transistors with self-aligned gate were fabricated with this method, which demonstrate the potential of this method as a candidate for mass production of graphene transistors.

Scalable Synthesis of Graphene on Patterned Ni and Transfer

Optimizing the fabrication process for high performance graphene field effect transistors

For the first time, we report a scalable technique to fabricate graphene transistors with self-aligned buried gates process. The high performance buried-gate graphene transistor has excellent field-effect mobility of 6,100cm2/V·s and 24,000 cm2/V·s before and after subtraction of contact resistance. To the best of our knowledge, this is the highest room temperature mobility for CVD graphene FETs reported to date. This result paves the way for manufacturable high quality graphene transistor technology.

Bo-Chao Huang

Papers

Impedance spectroscopy and equivalent circuits of conductively doped organic hole-transport materials

Contact resistance in top-gated graphene field-effect transistors

Scalable Synthesis of Graphene on Patterned Ni and Transfer

Optimizing the fabrication process for high performance graphene field effect transistors

High performance graphene FETs with self-aligned buried gates fabricated on scalable patterned ni-catalyzed graphene