Epitaxial Graphene Transistors: Enhancing Performance via Hydrogen Intercalation

Robinson, Joshua A.; Hollander, Matthew J.; LaBella, Michael; Trumbull, Kathleen A.; Cavalero, Randall; Snyder, David W.

doi:10.1021/nl2019855

Cited by 153 publications

(149 citation statements)

References 35 publications

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“…The ARPES data in Figs. 2(e) and 2(f) show a clear p-doping with the Dirac point %290 meV above the Fermi energy. The pdoping is consistent with previous studies of QFBLG, 10,11,26 even though the absolute degree of doping is somewhat stronger here. We derive a carrier concentration of ð71607Þ Â 10 12 holes=cm 2 .…”

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confidence: 92%

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Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

Barreto

Perkins

Johannsen

et al. 2013

Applied Physics Letters

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The electronic transport properties of epitaxial monolayer graphene (MLG) and hydrogen-intercalated quasi free-standing bilayer graphene (QFBLG) on SiC(0001) are investigated by micro multi-point probes. Using a probe with 12 contacts, we perform four-point probe measurements with the possibility to effectively vary the contact spacing over more than one order of magnitude, allowing us to establish that the transport is purely two-dimensional. Combined with the carrier density obtained by angle-resolved photoemission spectroscopy, we find the room temperature mobility of MLG to be (870±120) cm2/V s. The transport in QFBLG is also found to be two-dimensional with a mobility of (1600±160) cm2/V s.

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confidence: 92%

“…The hydrogen-induced QFBLG formation is known to lead to a higher mobility than for MLG. 11 More precisely, MLG and QFBLG were synthesized on top of semi-insulating 6H-SiC(0001) substrates with a resistivity exceeding 10 5 Xcm purchased from II-VI Inc. Details for the synthesis of MLG and hydrogen intercalation are found in Refs.…”

mentioning

confidence: 99%

Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

Barreto

Perkins

Johannsen

et al. 2013

Applied Physics Letters

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“…As-grown samples then consisted of a monolayer plus carbon buffer layer (CBL), and samples which were intercalated with hydrogen consisted of quasi-free standing graphene bilayers. [17][18][19] Processing began by patterning the SSD flange structures via electron beam lithography (EBL). The flanges were then etched in O 2 plasma.…”

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confidence: 99%

Graphene self-switching diodes as zero-bias microwave detectors

Westlund

Winters

Ivanov

et al. 2015

Applied Physics Letters

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Self-switching diodes (SSDs) were fabricated on as-grown and hydrogen-intercalated epitaxial graphene on SiC. The SSDs were characterized as zero-bias detectors with on-wafer measurements from 1 to 67 GHz. The lowest noise-equivalent power (NEP) was observed in SSDs on the hydrogen-intercalated sample, where a flat NEP of 2.2 nW/Hz 1 =2 and responsivity of 3.9 V/W were measured across the band. The measured NEP demonstrates the potential of graphene SSDs as zero-bias microwave detectors. Graphene exhibits electronic properties which are relevant for high-frequency applications 1 such as zero-bias detection in passive imaging arrays. 2 Detectors drawing zero bias current offer reduced 1/f-noise compared to biased detectors. Zero-bias detectors are today normally based on heterojunctions or Schottky diodes, reaching noise-equivalent power (NEP) below 20 pW/Hz 1 =2 beyond 100 GHz. 3,4 Zero-bias detection has been demonstrated in graphene field-effect transistors (FETs) with an NEP of 515 pW/Hz 1 =2 at 600 GHz. 5 Self-switching diodes (SSDs) offer a fundamentally different approach to zero-bias detection in which rectification and detection is achieved by a lateral field-effect. 6 Simulations have shown the feasibility of achieving rectification in graphene using SSD structures. 7,8 SSD detectors have previously been realized in other materials 9-12 with the most promising results for GaAs SSDs in which an NEP of 330 pW/Hz 1 =2 at 1.5 THz was observed. 13 In this work, detection with rectifying graphene SSDs at frequencies up to 67 GHz is demonstrated. The SSDs are realized in both as-grown (n-type) and hydrogen-intercalated (p-type) epitaxial graphene on SiC. Figure 1 shows a scanning electron micrograph of a single SSD channel fabricated in epitaxial graphene. The narrow graphene channel behaves as a lateral nanowire transistor. 6 The surrounding flanges act as lateral gates which are directly connected to the drain such that the drain voltage is simultaneously applied to the gates. This has the effect of modulating the carrier density in the nanowire channel generating a nonlinear current-voltage characteristic. 14 The inset shows an SSD design implemented for RF detection with nine nanowire channels acting in parallel to reduce resistance and NEP. 15 The SSDs were fabricated at the end of a 70 lm coplanar transmission line, in order to provide a partial RF match.Graphene was grown on the Si-face of two 20 Â 20 mm 2 nominally on-axis semi-insulating (SI) 4H-SiC substrates in a horizontal hot wall chemical vapor deposition (CVD) reactor. 16 Graphene growth was carried out at 1300 C to 1400 C in vacuum after an initial in-situ surface preparation of the substrates in a hydrogen/silane background. One of the samples was then intercalated in hydrogen at a temperature (pressure) of 800 C (500 mbar) in order to obtain quasi-free standing graphene. SSDs and supplementary test structures were fabricated on the graphene layers with and without H-intercalation. As-grown samples then consisted of a monolayer plus carbon buf...

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“…Epitaxial graphene residing on top of the bu er layer reconstruction of graphitized 6H-SiC(0001) is n-type doped [85,87,88] due to the combination of bulk and interface donor states [89,90] and has a Fermi energy 0.45 eV above the Dirac point. [90] In contrast, QFEG is known to be p-type doped.…”

Section: Charge Transfer In Tungsten Diselenide Epitaxial Graphene Hementioning

confidence: 99%

Layered Two-Dimensional Heterostructures and Their Tunneling Characteristics

Barrera¹

2017

Springer Theses

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Epitaxial Graphene Transistors: Enhancing Performance via Hydrogen Intercalation

Cited by 153 publications

References 35 publications

Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

Graphene self-switching diodes as zero-bias microwave detectors

Layered Two-Dimensional Heterostructures and Their Tunneling Characteristics

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