Contacting graphene

Robinson, Joshua A.; LaBella, Michael; Zhu, Meng; Hollander, Matt; Kasarda, Richard; Hughes, Zachary; Trumbull, Kathleen A.; Cavalero, Randal; Snyder, David W.

doi:10.1063/1.3549183

Cited by 325 publications

(314 citation statements)

References 16 publications

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“…E-mail: Thomas.Seyller@physik.tu-chemnitz.de (Thomas Seyller) dependent [4] and it has been observed that this is a direct consequence of the presence of the buffer layer [10]. In recent years, various elements such as gold [11], lithium [12], silicon [13], fluorine [14], germanium [15], oxygen [16][17][18][19] and hydrogen [10,[20][21][22][23] have been intercalated between the buffer layer and SiC(0001) in order to modify the interface.…”

Section: Introductionmentioning

confidence: 99%

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Buffer layer free graphene on SiC(0001) via interface oxidation in water vapor

Ostler

Fromm

Koch

et al. 2014

Carbon

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Intercalation of various elements has become a popular technique to decouple the buffer layer of epitaxial graphene on SiC(0001) from the substrate. Among many other elements, oxygen can be used to passivate the SiC interface, causing the buffer layer to transform into graphene. Here, we study a gentle oxidation of the interface by annealing buffer layer and monolayer graphene samples in water vapor. X-ray photoelectron spectroscopy demonstrates the decoupling of the buffer layer from the SiC substrate. Raman spectroscopy is utilized to investigate a possible introduction of defects. Angle-resolved photoemission spectroscopy shows that the electronic structure of the water vapor treated samples. Low-energy electron microscopy (LEEM) measurements demonstrate that the decoupling takes place without changes in the surface morphology. The LEEM reflectivity spectra are discussed in terms of two different interpretations.

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Section: Introductionmentioning

confidence: 99%

“…Hydrogen has been shown to work well, leading to so-called quasi-free-standing monolayer graphene (QFMLG) with improved electrical properties [10,[22][23]] when compared to normal MLG which resides on the buffer layer. Hydrogen is therefore a prime candidate for the future integration of quasi-free-standing graphene into devices.…”

Section: Introductionmentioning

confidence: 99%

Buffer layer free graphene on SiC(0001) via interface oxidation in water vapor

Ostler

Fromm

Koch

et al. 2014

Carbon

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“…This resistance is a limiting factor for the performance of electronic devices, and an increasing amount of research has concentrated on this issue. [2][3][4][5][6][7][8] The relative contribution of contact resistance to the total device resistance becomes larger in devices with shorter inter-electrode spacings, i.e., in shorter channel devices. Therefore, contact resistance becomes a predominant factor to consider when attempting to achieve miniaturization and integration of graphene devices.…”

Section: Introductionmentioning

confidence: 99%

Observation of negative contact resistances in graphene field-effect transistors

Nouchi

Saito

Tanigaki

2012

Journal of Applied Physics

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The gate-voltage (V G ) dependence of the contact resistance (R C ) in graphene field-effect transistors is characterized by the transmission line model. The R C -V G characteristics of Ag, Cu, and Au contacts display a dip around the charge neutrality point, and become even negative with Ag contacts. The dip structure is well reproduced by a model calculation that considers a metal-contact-induced potential variation near the metal contact edges. The apparently negative R C originates with the carrier doping from the metal contacts to the graphene channel and appears when the doping effect is more substantial than the actual contact resistance precisely at the contacts. The negative R C can appear at the metal contacts to Dirac-cone systems such as graphene.

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“…3,4 R C for contacts formed to epitaxial graphene on SiC have been reported to be less than 100 Ω μm 5 and with specific contact resistivity (ρ c ) of order 10 -7 Ω cm 2 . 5,6 Reported values of R c for chemical vapor deposited (CVD) graphene typically range from 500 Ω μm to 1000 Ω μm. 7,8 Despite the technological attractiveness of CVD grown graphene, these contact resistances remain too large for most applications and are far from that reported for contacts to epitaxial graphene on SiC.…”

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confidence: 99%

Ultraviolet/ozone treatment to reduce metal-graphene contact resistance

Li¹,

Liang²,

Yu³

et al. 2013

Applied Physics Letters

118

105

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We report reduced contact resistance of single-layer graphene devices by using ultraviolet ozone (UVO) treatment to modify the metal/graphene contact interface. The devices were fabricated from mechanically transferred, chemical vapor deposition (CVD) grown, single layer graphene. UVO treatment of graphene in the contact regions as defined by photolithography and prior to metal deposition was found to reduce interface contamination originating from incomplete removal of poly(methyl methacrylate) (PMMA) and photoresist. Our control experiment shows that exposure times up to 10 minutes did not introduce significant disorder in the graphene as characterized by Raman spectroscopy. By using the described approach, contact resistance of less than 200 Ω μm was achieved, while not significantly altering the electrical properties of the graphene channel region of devices.

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Contacting graphene

Cited by 325 publications

References 16 publications

Buffer layer free graphene on SiC(0001) via interface oxidation in water vapor

Buffer layer free graphene on SiC(0001) via interface oxidation in water vapor

Observation of negative contact resistances in graphene field-effect transistors

Ultraviolet/ozone treatment to reduce metal-graphene contact resistance

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