Fabrication of high-quality all-graphene devices with low contact resistances
TL;DR: In this article, a clean fabrication strategy for all-graphene devices via a defect-assisted anisotropic etching was reported, where the as-fabricated graphene is free of contamination and retains the quality of pristine graphene.
Abstract: All-graphene devices are new class of graphene devices with simple layouts and low contact resistances. Here we report a clean fabrication strategy for all-graphene devices via a defect-assisted anisotropic etching. The as-fabricated graphene is free of contamination and retains the quality of pristine graphene. The contact resistance at room temperature (RT) between a bilayer graphene channel and a multilayer graphene electrode can be as low as ∼5 Ω·μm, the lowest ever achieved experimentally. Our results suggest the feasibility of employing such all-graphene devices in high performance carbon-based integrated circuits.
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TL;DR: This work carefully engineered graphene oxide (GO) as a vaccine adjuvant for immunotherapy using urease B (Ure B) as the model antigen and presents a novel, highly effective GO-based vaccine nano-adjuvant, which highlights the critical roles of surface chemistry for the rational design of nano- adjuvants.
Abstract: Benefiting from their unique physicochemical properties, graphene derivatives have attracted great attention in biomedicine. In this study, we carefully engineered graphene oxide (GO) as a vaccine adjuvant for immunotherapy using urease B (Ure B) as the model antigen. Ure B is a specific antigen for Helicobacter pylori, which is a class I carcinogen for gastric cancer. Polyethylene glycol (PEG) and various types of polyethylenimine (PEI) were used as coating polymers. Compared with single-polymer modified GOs (GO–PEG and GO–PEI), certain dual-polymer modified GOs (GO–PEG–PEI) can act as a positive modulator to promote the maturation of dendritic cells (DCs) and enhance their cytokine secretion through the activation of multiple toll-like receptor (TLR) pathways while showing low toxicity. Moreover, this GO–PEG–PEI can serve as an antigen carrier to effectively shuttle antigens into DCs. These two advantages enable GO–PEG–PEI to serve as a novel vaccine adjuvant. In the subsequent in vivo experiments, compared with free Ure B and clinically used aluminum-adjuvant-based vaccine (Alum-Ure B), GO–PEG–PEI–Ure B induces stronger cellular immunity via intradermal administration, suggesting promising applications in cancer immunotherapy. Our work not only presents a novel, highly effective GO-based vaccine nano-adjuvant, but also highlights the critical roles of surface chemistry for the rational design of nano-adjuvants.
76 citations
TL;DR: In this article, the authors present the highlights of current advances regarding utilization of various plasmas for the control of graphene thickness and compare the mechanisms involved in the etching phenomenon of the graphene sheet to realize the layer control.
27 citations
TL;DR: In this article, the patterning of monolayer graphene nanostructures with zigzag edges on hexagonal boron nitride (h-BN) substrates by an anisotropic etching technique was reported.
Abstract: Graphene nanostructures are potential building blocks for nanoelectronic and spintronic devices. However, the production of monolayer graphene nanostructures with well-defined zigzag edges remains a challenge. In this paper, we report the patterning of monolayer graphene nanostructures with zigzag edges on hexagonal boron nitride (h-BN) substrates by an anisotropic etching technique. We found that hydrogen plasma etching of monolayer graphene on h-BN is highly anisotropic due to the inert and ultra-flat nature of the h-BN surface, resulting in zigzag edge formation. The as-fabricated zigzag-edged monolayer graphene nanoribbons (Z-GNRs) with widths below 30 nm show high carrier mobility and width-dependent energy gaps at liquid helium temperature. These high quality Z-GNRs are thus ideal structures for exploring their valleytronic or spintronic properties.
23 citations
TL;DR: In this article, the electronic and electrical properties of siligraphene (g-SiC3) under various percentages of strain have been investigated based on the first principles density functional theory.
18 citations
TL;DR: In this article, a graphene-wrapped MnO/CNFs@G membrane with uniform MnO particle distribution in porous carbon nanofibers and with a graphene layer covering not only facilitates the transport of both electrolyte ions and electrons to the MnO surface, but also relieves the pulverization that originated from the large volume change of MnO during charge/discharge cycles.
Abstract: In this work, we have fabricated a graphene-wrapped MnO/carbon nanofibers (MnO/CNFs@G) membrane by a facile electrospinning technique followed by an ambient pressure chemical vapor deposition (APCVD) process. The resultant MnO/CNFs@G membrane with uniform MnO particle distribution in porous carbon nanofibers and with a graphene layer covering not only facilitates the transport of both electrolyte ions and electrons to the MnO surface, but also relieves the pulverization that originated from the large volume change of MnO during the charge/discharge cycles. Interestingly, the free-standing and binder-free MnO/CNFs@G membranes can deliver a high reversible capacity of 946.5 mA h g−1 when the current density is switched back to 0.1 A g−1 after 110 cycles. Even at a high rate (10 A g−1), the electrode can still keep 426.7 mA h g−1 after 5000 cycles with coulombic efficiency of above 99%. This is the best specific capacity and longest cycling life reported for the MnO composite film anodes. We believe that the approach based on CNFs and CVD graphene as a structural support for the transition metal oxide can be potentially extended to improve the electrochemical performance of other electrode materials in lithium ion batteries.
15 citations
References
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TL;DR: Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena can now be mimicked and tested in table-top experiments.
Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
35,293 citations
"Fabrication of high-quality all-gra..." refers background in this paper
...Graphene is an ideal building block for electronic devices due to its extraordinary properties [1]....
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TL;DR: This work reviews recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.
Abstract: Recent years have witnessed many breakthroughs in research on graphene (the first two-dimensional atomic crystal) as well as a significant advance in the mass production of this material. This one-atom-thick fabric of carbon uniquely combines extreme mechanical strength, exceptionally high electronic and thermal conductivities, impermeability to gases, as well as many other supreme properties, all of which make it highly attractive for numerous applications. Here we review recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.
7,987 citations
"Fabrication of high-quality all-gra..." refers background in this paper
...Indeed, prototypes of high-frequency transistors, flexible electronics, photonic devices and sensing devices have been demonstrated in the laboratory and shown to have superior performance to other devices [2]....
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TL;DR: In this article, the authors focus on the origin of the D and G peaks and the second order of D peak and show that the G and 2 D Raman peaks change in shape, position and relative intensity with number of graphene layers.
6,496 citations
"Fabrication of high-quality all-gra..." refers background in this paper
...Compared with the pristine graphene, both the thinned SLG and BLG show similar Raman characteristics in terms of fairly low D-peak intensity, D-/G- peak positions, and full width at half maximum height (FWHM) of both G and 2D peaks, showing that the high quality has been preserved [22]....
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TL;DR: In this paper, it was shown that the Klein paradox can be tested in a conceptually simple condensed-matter experiment using electrostatic barriers in single and bi-layer graphene, showing that quantum tunnelling in these materials becomes highly anisotropic, qualitatively different from the case of normal, non-relativistic electrons.
Abstract: The so-called Klein paradox—unimpeded penetration of relativistic particles through high and wide potential barriers—is one of the most exotic and counterintuitive consequences of quantum electrodynamics. The phenomenon is discussed in many contexts in particle, nuclear and astro-physics but direct tests of the Klein paradox using elementary particles have so far proved impossible. Here we show that the effect can be tested in a conceptually simple condensed-matter experiment using electrostatic barriers in single- and bi-layer graphene. Owing to the chiral nature of their quasiparticles, quantum tunnelling in these materials becomes highly anisotropic, qualitatively different from the case of normal, non-relativistic electrons. Massless Dirac fermions in graphene allow a close realization of Klein’s gedanken experiment, whereas massive chiral fermions in bilayer graphene offer an interesting complementary system that elucidates the basic physics involved.
3,402 citations
"Fabrication of high-quality all-gra..." refers background in this paper
...metal-doped graphene and channel graphene limits the carrier tunneling probability H T [32]....
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