Structured epitaxial graphene on SiC

Ruan, Ming; Hu, Yusheng; Guo, Zelei; Dong, Rui; Palmer, James; Hankinson, John; Berger, Claire; Heer, Walt A. de; Chakraborty, Partha Sarathi; Lourenco, Nelson E.; Cressler, John D.

doi:10.1109/iscdg.2012.6359994

Cited by 4 publications

(6 citation statements)

References 14 publications

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“…Note that the plateau is almost exactly 1 G0 , precisely as observed in ≈ 1µm wide ribbons on nonpolar epigraphene [11], in ≈ 40 nm wide epigraphene ribbons on the sidewalls of steps etched in SiC, [10] and, originally in meandering ≈ 40 nm wide epigraphene ribbons that decorate natural steps on SiC [61]. We again see it here on 435 µm long ribbons that are decoupled from the SiC substrate.…”

Section: Top-gated Seg and Qfsgsupporting

confidence: 60%

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Heer

Zhao

et al. 2023

Preprint

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Epigraphene, which is graphene that is epitaxially grown on a single crystal silicon carbide (SiC) substrate, was proposed as a path to extend Moore’s roadmap beyond silicon at the beginning of the millennium. Despite considerable progress, the lack of a bandgap in graphene and steps on the substrate continued to be roadblocks. Here we show a new method to produce millimeter scale step-free terraces covered with a graphene-like interface that is bonded to the SiC surface. This so-called buffer layer is found to be two-dimensional semiconducting epigraphene (SEG) with a 0.6 eV bandgap and a room temperature mobility exceeding 4000 cm2V-1s-1, which surpasses all current 2D single layer semiconductors by a factor of 10. A top-gated SEG field-effect transistor demonstrates an on-to-off ratio of 104 which is suitable for digital electronics. In addition, we also find that hydrogen intercalation converts SEG into a high-mobility semi-metallic epigraphene monolayer that can be seamlessly integrated with SEG. Centimeter scale mean free paths are observed in the epigraphene edge state of this quasi-freestanding monolayer, which is by a factor of 1000, the largest room temperature electronic mean free path observed in any material.

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Section: Top-gated Seg and Qfsgsupporting

confidence: 60%

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Heer

Zhao

et al. 2023

Preprint

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“…On the C-face, N is determined by both T (1450 °C-1525 °C) and time (1 min to several hours for very thick films) [597,615] [606] (see section IV.1.3 and figures IV.5(a)-(c)). Templated graphene growth of nanostructures (e.g.SiC sidewalls [618][619][620]) on non-polar facets (i.e. other that (0 0 0 1) and 0 0 0 1 ) is finely tuned close to the buffer layer growth conditions.…”

Section: Iv12 Near Equilibrium Confinement Controlled Growthmentioning

confidence: 99%

“…Masking methods, for selective growth using AlN [727], SiN [728] and amorphous C masks [642] with tens of nm precision have been proposed. The template growth method on sidewalls of SiC trenches [604,615,618,619] is described below. It circumvents the detrimental effect of traditional plasma etching [729,730] and resulting sidewall nanoribbons show RT ballistic transport properties [620].…”

Section: Iv110 Structured Growthmentioning

confidence: 99%

Production and processing of graphene and related materials

et al. 2020

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We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a ‘hands-on’ approach, providing practical details and procedures as derived from literature as well as from the authors’ experience, in order to enable the reader to reproduce the results. Section is devoted to ‘bottom up’ approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section covers ‘top down’ techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers’ and modified Hummers’ methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by ...

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“…In a transport measurement, an external voltage V creates a difference of chemical potential between two contacts u − −u + = eV and generates a net current [25,26] k k…”

Section: Science China Materialsmentioning

confidence: 99%

“…the net current can be written as I = 2×e/h(u − −u + ) [ 25,26]. The factor 2 in Equation (3) comes from the spin degree of freedom.…”

Section: Science China Materialsmentioning

confidence: 99%

Origin of room-temperature single-channel ballistic transport in zigzag graphene nanoribbons

Chu

2015

Sci. China Mater.

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were grown on the slope of a terraced silicon carbide surface and the transport properties of the GNRs were measured in situ with variable probe spacing. Fig. 1 summarizes the room-temperature conductance G vs. the probe spacing L of the zigzag GNRs in a range of energies around charge neutrality [15]. For L ≤ 160 nm, a conductance of G 0 is observed. With increasing the probe spacing to L ~ 1 μm, the conductance decreases gradually to G 0 /2, then it keeps a robust value of G 0 /2 for 1 μm ≤ L ≤ 16 μm. The most surprising result of their experiments is the observation of the singl e quantum mechanical channel for transport in these high-quality zigzag GNRs with 1 μm ≤ L ≤ 16 μm. This result is amazing since that at lea st an edge-degenerate channel, giving rise to a conductance of G 0 , should be involved in the transport of the GN Rs in a range of energies around charge neutrality point [16,17]. The observ ed conductance of G 0 /2, as shown in Fig. 1, is obviously beyond the description of any previous theories [18].

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Structured epitaxial graphene on SiC

Cited by 4 publications

References 14 publications

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Ultrahigh mobility semiconducting epitaxial graphene on silicon carbide

Production and processing of graphene and related materials

Origin of room-temperature single-channel ballistic transport in zigzag graphene nanoribbons

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