Phase Space for the Breakdown of the Quantum Hall Effect in Epitaxial Graphene

Alexander-Webber, Jack A.; Baker, A. M. R.; Janssen, T. J. B. M.; Tzalenchuk, Alexander; Lara‐Avila, Samuel; Kubatkin, Sergey; Yakimova, Rositsa; Piot, B. A.; Maude, D. K.; Nicholas, R.J.

doi:10.1103/physrevlett.111.096601

Cited by 41 publications

(61 citation statements)

References 32 publications

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“…At I ¼ 100 μA, R xx > 3 Ω over the whole magnetic field range, yielding a longitudinal voltage (V xx > 300 μV) too large to be compatible with metrological measurements. This defines a critical breakdown current I c ≃ 1 A=m, one order of magnitude lower than the highest reported values for graphene on SiC [8]. Moreover, R xx ðBÞ does not have any more a unique minimum associated to ν ¼ 2 but shows oscillations periodic in 1=B.…”

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confidence: 94%

“…In this Letter, we consider graphene deposited on top of a SiC substrate (G=SiC). In this system, the quantum Hall plateau at h=2e 2 is exceptionally robust with respect to magnetic field [8]. Moreover, G=SiC shows metrological quantum Hall quantization, with relative accuracies of the quantized resistance better than 10 −9 [9], even at lower magnetic fields and higher temperatures than GaAs-based quantum Hall resistance standards [10].…”

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confidence: 99%

“…Moreover, G=SiC shows metrological quantum Hall quantization, with relative accuracies of the quantized resistance better than 10 −9 [9], even at lower magnetic fields and higher temperatures than GaAs-based quantum Hall resistance standards [10]. In this context, it is important to unveil the role of charge reservoirs in the stabilization of the first quantum Hall plateau [11,12] and to identify the mechanisms governing the breakdown of the QHE [8,13,14].…”

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Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect

et al. 2016

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We report on the stability of the quantum Hall plateau in wide Hall bars made from a chemically gated graphene film grown on SiC. The ν ¼ 2 quantized plateau appears from fields B ≃ 5 T and persists up to B ≃ 80 T. At high current density, in the breakdown regime, the longitudinal resistance oscillates with a 1=B periodicity and an anomalous phase, which we relate to the presence of additional electron reservoirs. The high field experimental data suggest that these reservoirs induce a continuous increase of the carrier density up to the highest available magnetic field, thus enlarging the quantum plateaus. These in-plane inhomogeneities, in the form of high carrier density graphene pockets, modulate the quantum Hall effect breakdown and decrease the breakdown current. DOI: 10.1103/PhysRevLett.117.237702 Graphene [1,2] shows a unique half-integer quantum Hall effect (QHE) with conductivity plateaus σ xy ¼ 4ðm þ 1=2Þe 2 =h, where the factor 4 stands for the spin and valley degeneracies and m ¼ 0; AE1; AE2; … [3]. The peculiar dispersion E m ≃ AE420 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi jmjB½T p K of the Landau levels (LLs) in graphene induces large energy gaps at low LL indices and allows us to explore exotic transport phenomena even at relatively high temperature [4]. The substrate graphene is deposited on plays a central role in determining the features of the observed QHE. In lowmobility graphene on SiO 2 , the presence of electron-hole puddles at the charge neutrality point (CNP) prevents any divergence of the longitudinal resistance at filling factor ν < 2, whereas the Hall resistivity fluctuates around zero due to charge compensation [5]. On the other hand, in high mobility graphene deposited on boron nitride flakes, a complete degeneracy lifting of the Landau levels can be observed and the corresponding spin-valley textures have been identified [6,7]. In this Letter, we consider graphene deposited on top of a SiC substrate (G=SiC). In this system, the quantum Hall plateau at h=2e 2 is exceptionally robust with respect to magnetic field [8]. Moreover, G=SiC shows metrological quantum Hall quantization, with relative accuracies of the quantized resistance better than 10 −9 [9], even at lower magnetic fields and higher temperatures than GaAs-based quantum Hall resistance standards [10]. In this context, it is important to unveil the role of charge reservoirs in the stabilization of the first quantum Hall plateau [11,12] and to identify the mechanisms governing the breakdown of the QHE [8,13,14].In the following, we report on the results obtained from graphene samples grown by Graphensic AB company on the Si face of a 4H-SiC substrate. The details concerning the growth conditions can be found in Ref. [15]. The samples are tailored into Hall bar geometry with a width W ¼ 100 μm and a total length of 420 μm. The as-grown carrier density of G=SiC is of the order of 1 × 10 13 cm −2 and is reduced to about ≃5 × 10 11 cm −2 using a polymer gate (photochemical doping) [15]. The mobility at T ¼ 4 K is ab...

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Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect

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“…On the other hand, similar to graphene obtained by drawing or peel off method, SiC-epitaxial graphene displays extremely large, temperature independent mobility but not as high as exfoliated graphene [96]. Even without transfer, graphene obtained through this method displays massless Dirac fermions [85,[96][97][98][99][100][101]. In multi-layered epitaxial graphene, weak van der Waals forces responsible for multilayer cohesion do not necessarily impact electronic properties of individual sheets within a stack.…”

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confidence: 99%

Graphene synthesis: a Review

Shams

Zhang

Zhu

2015

Materials Science-Poland

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Graphene has achieved a great amount of popularity and interest from the science world because of its extraordinary physical, mechanical and thermal properties. Graphene is an allotrope of carbon, having one-atom-thick planar sheets of sp 2 bonded carbon atoms densely packed in a honeycomb crystal lattice. Many methods to synthesize graphene have been developed over a short period and we believe it is necessary to create a list of the most notable approaches. This article focuses on the methods to synthesize graphene in an attempt to summarize and document advancements in the synthesis of graphene research and future prospects.

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“…the maximum current that the material can sustain before quantum Hall vanishes), since this was an order of magnitude lower than what is achievable in SiC/G. 7 Together with opportunities to measure at relatively low fields, 8 SiC/G represents a very promising platform for QHR standards with robust performance and high precision.…”

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Low contact resistance in epitaxial graphene devices for quantum metrology

et al. 2015

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We investigate Ti/Au contacts to monolayer epitaxial graphene on SiC (0001) for applications in quantum resistance metrology. Using three-terminal measurements in the quantum Hall regime we observed variations in contact resistances ranging from a minimal value of 0.6 Omega up to 11 k Omega. We identify a major source of high-resistance contacts to be due bilayer graphene interruptions to the quantum Hall current, whilst discarding the effects of interface cleanliness and contact geometry for our fabricated devices. Moreover, we experimentally demonstrate methods to improve the reproducibility of low resistance contacts (less than 10 Omega) suitable for high precision quantum resistance metrology.

Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; Swedish-Korean Basic Research Cooperative Program of the NRF [2014R1A2A1A1 2067266]; EMRP project GraphOhm; EMRP within EURAMET; EMRP within European Union

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Phase Space for the Breakdown of the Quantum Hall Effect in Epitaxial Graphene

Cited by 41 publications

References 32 publications

Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect

Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect

Graphene synthesis: a Review

Low contact resistance in epitaxial graphene devices for quantum metrology

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