Low contact resistance in epitaxial graphene devices for quantum metrology

Yager, Tom; Lartsev, Arseniy; Cedergren, Karin; Yakimova, Rositsa; Panchal, Vishal; Kazakova, Olga; Tzalenchuk, Alexander; Kim, Kyung Ho; Park, Yung Woo; Lara‐Avila, Samuel; Kubatkin, Sergey

doi:10.1063/1.4928653

Cited by 21 publications

(21 citation statements)

References 36 publications

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“…26 We get values as low as 14 X lm which is slightly less than that reported for hBN-encapsulated graphene 11 and is much lower than the resistance of typical surface contacts. 27 We have also performed the critical current measurements for one of the devices, depicted in Figure 7.…”

Section: -2mentioning

confidence: 74%

Encapsulation of graphene in Parylene

Skoblin

Sun

Yurgens

2017

Applied Physics Letters

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Graphene encapsulated between flakes of hexagonal boron nitride (hBN) demonstrates the highest known mobility of charge carriers. However, the technology is not scalable to allow for arrays of devices. We are testing a potentially scalable technology for encapsulating graphene where we replace hBN with Parylene while still being able to make low-ohmic edge contacts. The resulting encapsulated devices show low parasitic doping and a robust Quantum Hall effect in relatively low magnetic fields <5 T. Published by AIP Publishing. [http://dx

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Section: -2mentioning

confidence: 74%

Encapsulation of graphene in Parylene

Skoblin

Sun

Yurgens

2017

Applied Physics Letters

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“…Graphene layers grown epitaxially on SiC wafers are an attractive solution for upscaling graphene-based electronic devices for a variety of applications such as sensing, spintronics, and electrical metrology [1,2,3,4]. Although SiC provides a naturally insulating substrate and direct growth avoids contamination and sample degradation incurred during transfer or exfoliation, reproducing the behaviour of pristine exfoliated prototypes is not straightforward due to patches of bilayer graphene [5] and interactions with the underlying SiC substrate. Charge transfer from interfacial states in the buffer layer actually improves the robustness of graphene for quantum resistance metrology and provides a natural mechanism for breaking layer-symmetry and opening a band gap in bilayers [6], but may have an adverse affect on carrier mobility and tunability.…”

Section: Introductionmentioning

confidence: 99%

Observation of Coulomb blockade in nanostructured epitaxial bilayer graphene on SiC

Chua

Lartsev

Sui

et al. 2017

Carbon

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We study electron transport in nanostructures patterned in bilayer graphene patches grown epitaxially on SiC as a function of doping, magnetic field, and temperature. Away from charge neutrality transport is only weakly modulated by changes in carrier concentration induced by a local side-gate. At low ntype doping close to charge neutrality, electron transport resembles that in exfoliated graphene nanoribbons and is well described by tunnelling of single electrons through a network of Coulomb-blockaded islands. Under the influence of an external magnetic field, Coulomb blockade resonances fluctuate around an average energy and the gap shrinks as a function of magnetic field. At charge neutrality, however, conduction is less insensitive to external magnetic fields. In this regime we also observe a stronger suppression of the conductance below T * , which we interpret as a sign of broken interlayer symmetry or strong fluctuations in the edge/potential disorder.

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“…While growth of graphene on the C-face (0001) of SiC substrates is difficult to control, the Si-face (0001) provides high quality, homogenous monolayer (ML) and bilayer (BL) graphene at a wafer scale, due to a self-consistent nature of the growth process [3][4][5]. Prototype devices based on EG have been demonstrated [6][7][8][9].…”

Section: Epitaxial Graphenementioning

confidence: 99%

Study of novel electronic materials by mid-infrared and terahertz optical Hall effect

Armakavicius¹

2017

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Development of silicon based electronics have revolutionized our every day life during the last three decades. Nowadays Si based devices operate close to their theoretical limits that is becoming a bottleneck for further progress. In particular, for the growing field of high frequency and high power electronics, Si cannot offer the required properties. Development of materials capable of providing high current densities, carrier mobilities and high breakdown fields is crucial for a progress in state of the art electronics. Epitaxial graphene grown on semi-insulating silicon carbide substrates has a high potential to be integrated in the current planar device technologies. High electron mobilities and sheet carrier densities make graphene extremely attractive for high frequency analog applications. One of the remaining challenges is the interaction of epitaxial graphene with the substrate. Typically, much lower free charge carrier mobilities, compared to free standing graphene, and doping, due to charge transfer from the substrate, is reported. Thus, a good understanding of the intrinsic free charge carriers properties and the factors affecting them is very important for further development of epitaxial graphene. III-group nitrides have been extensively studied and already have proven their high efficiency as light sources for short wavelengths. High carrier mobilities and breakdown electric fields were demonstrated for III-group nitrides, making them attractive for high frequency and high power applications. Currently, In-rich InGaN alloys and AlGaN/GaN high electron mobility structures are of high interest for the research community due to open fundamental questions. Electrical characterization techniques, commonly used for the determination of free charge carrier properties, require good ohmic and Schottky contacts, which in certain cases can be difficult to achieve. Access to electrical properties of buried conductive channels in multilayered structures requires modification of samples and good knowledge of the electrical properties of all electrical contact within the structure. Moreover, the use of electrical contacts to electrically characterize two-dimensional electronic materials, such as graphene, can alter their intrinsic properties. Furthermore, the determination of effective mass parameters commonly employs cyclotron resonance and Shubnikov-de Haas oscillations measurements, which require long scattering times of free charge carriers, high magnetic fields and low temperatures. The optical Hall effect is an external magnetic field induced optical anisotropy in conductive layers due to the motion of the free charge carriers under the influence of the Lorentz force, and is equivalent to the electrical Hall effect at optical frequencies. The optical Hall effect can be measured by generalized ellipsometry and provides a powerful method for the determination of free charge carrier properties in a non-destructive and contactless manner. In principle, a single optical Hall effect measurement can provide quan...

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Low contact resistance in epitaxial graphene devices for quantum metrology

Cited by 21 publications

References 36 publications

Encapsulation of graphene in Parylene

Encapsulation of graphene in Parylene

Observation of Coulomb blockade in nanostructured epitaxial bilayer graphene on SiC

Study of novel electronic materials by mid-infrared and terahertz optical Hall effect

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