Dielectric Surface Charge Engineering for Electrostatic Doping of Graphene

Wittmann, Sigrid; Aumer, Fabian; Wittmann, Doris; Pindl, Stephan; Wagner, Stefan; Gahoi, Amit; Reato, Eros; Belete, Melkamu; Kataria, Satender

doi:10.1021/acsaelm.0c00051

Cited by 15 publications

(18 citation statements)

References 62 publications

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“…[ 57 ] Therefore, it is important to fabricate high quality graphene to lower R SK and thus to reduce R CF . [ 58 ] Also selecting the metal materials that increase n 0 in the underneath graphene would improve R SK and hence R CF .…”

Section: Resultsmentioning

confidence: 99%

“…In the case of graphene, n0 typically varies between 10 11 and 10 13 cm -2 , therefore RCF is intrinsically dependent on the RSK of graphene under the metal contact [57]. Therefore, it is important to fabricate high quality graphene to lower RSK and thus to reduce RCF [58]. Also selecting the metal materials that increase n0 in the underneath graphene would improve RSK and hence RCF.…”

Section: Resultsmentioning

confidence: 99%

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Dependable Contact Related Parameter Extraction in Graphene–Metal Junctions

Gahoi

Kataria

Driussi

et al. 2020

Adv Elect Materials

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The accurate extraction and the reliable, repeatable reduction of graphene–metal contact resistance (RC) are still open issues in graphene technology. Here, the importance of following clear protocols when extracting RC using the transfer length method (TLM) is demonstrated. The example of back‐gated graphene TLM structures with nickel contacts, a complementary metal oxide semiconductor compatible metal, is used here. The accurate extraction of RC is significantly affected by generally observable Dirac voltage shifts with increasing channel lengths in ambient conditions. RC is generally a function of the carrier density in graphene. Hence, the position of the Fermi level and the gate voltage impact the extraction of RC. Measurements in high vacuum, on the other hand, result in dependable extraction of RC as a function of gate voltage owing to minimal spread in Dirac voltages. The accurate measurement and extraction of important parameters like contact‐end resistance, transfer length, sheet resistance of graphene under the metal contact, and specific contact resistivity as a function of the back‐gate voltage is further assessed. The presented methodology has also been applied to devices with gold and copper contacts, with similar conclusions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Dependable Contact Related Parameter Extraction in Graphene–Metal Junctions

Gahoi

Kataria

Driussi

et al. 2020

Adv Elect Materials

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“…The Silicon nitride, , dielectric layer causes an effective n-type doping in graphene sheet 34 , 35 . The shift in Fermi energy is given by where is the Fermi velocity ( for graphene), is Planck’s constant, and n is the carrier density.…”

Section: Appendixmentioning

confidence: 99%

Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene

Shabbir

2020

Sci Rep

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We present a proof of concept for a spectrally selective thermal mid-IR source based on nanopatterned graphene (NPG) with a typical mobility of CVD-grown graphene (up to 3000 $$\hbox {cm}^2\,\hbox {V}^{-1}\,\hbox {s}^{-1}$$ cm 2 V - 1 s - 1 ), ensuring scalability to large areas. For that, we solve the electrostatic problem of a conducting hyperboloid with an elliptical wormhole in the presence of an in-plane electric field. The localized surface plasmons (LSPs) on the NPG sheet, partially hybridized with graphene phonons and surface phonons of the neighboring materials, allow for the control and tuning of the thermal emission spectrum in the wavelength regime from $$\lambda =3$$ λ = 3 to 12 $$\upmu$$ μ m by adjusting the size of and distance between the circular holes in a hexagonal or square lattice structure. Most importantly, the LSPs along with an optical cavity increase the emittance of graphene from about 2.3% for pristine graphene to 80% for NPG, thereby outperforming state-of-the-art pristine graphene light sources operating in the near-infrared by at least a factor of 100. According to our COMSOL calculations, a maximum emission power per area of $$11\times 10^3$$ 11 × 10 3 W/$$\hbox {m}^2$$ m 2 at $$T=2000$$ T = 2000 K for a bias voltage of $$V=23$$ V = 23 V is achieved by controlling the temperature of the hot electrons through the Joule heating. By generalizing Planck’s theory to any grey body and deriving the completely general nonlocal fluctuation-dissipation theorem with nonlocal response of surface plasmons in the random phase approximation, we show that the coherence length of the graphene plasmons and the thermally emitted photons can be as large as 13 $$\upmu$$ μ m and 150 $$\upmu$$ μ m, respectively, providing the opportunity to create phased arrays made of nanoantennas represented by the holes in NPG. The spatial phase variation of the coherence allows for beamsteering of the thermal emission in the range between $$12^\circ$$ 12 ∘ and $$80^\circ$$ 80 ∘ by tuning the Fermi energy between $$E_F=1.0$$ E F = 1.0 eV and $$E_F=0.25$$ E F = 0.25 eV through the gate voltage. Our analysis of the nonlocal hydrodynamic response leads to the conjecture that the diffusion length and viscosity in graphene are frequency-dependent. Using finite-difference time domain calculations, coupled mode theory, and RPA, we develop the model of a mid-IR light source based on NPG, which will pave the way to graphene-based optical mid-IR communication, mid-IR color displays, mid-IR spectroscopy, and virus detection.

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“…However, the native oxide layer can be present at the graphene and silicon interface because silicon surface reoxidation after direct graphene synthesis was reported in [ 62 ]. Graphene placed on the silicon dioxide can be electron-doped due to the positive silanol groups on the SiO 2 surface [ 97 , 98 ].…”

Section: Discussionmentioning

confidence: 99%

The Graphene Structure’s Effects on the Current-Voltage and Photovoltaic Characteristics of Directly Synthesized Graphene/n-Si(100) Diodes

et al. 2022

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Graphene was synthesized directly on Si(100) substrates by microwave plasma-enhanced chemical vapor deposition (MW-PECVD). The effects of the graphene structure on the electrical and photovoltaic properties of graphene/n-Si(100) were studied. The samples were investigated using Raman spectroscopy, atomic force microscopy, and by measuring current–voltage (I-V) graphs. The temperature of the hydrogen plasma annealing prior to graphene synthesis was an essential parameter regarding the graphene/Si contact I-V characteristics and photovoltaic parameters. Graphene n-type self-doping was found to occur due to the native SiO2 interlayer at the graphene/Si junction. It was the prevalent cause of the significant decrease in the reverse current and short-circuit current. No photovoltaic effect dependence on the graphene roughness and work function could be observed.

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Dielectric Surface Charge Engineering for Electrostatic Doping of Graphene

Cited by 15 publications

References 62 publications

Dependable Contact Related Parameter Extraction in Graphene–Metal Junctions

Dependable Contact Related Parameter Extraction in Graphene–Metal Junctions

Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene

The Graphene Structure’s Effects on the Current-Voltage and Photovoltaic Characteristics of Directly Synthesized Graphene/n-Si(100) Diodes

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