Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics

Bartolomeo, Antonio Di; Giubileo, Filippo; Romeo, Francesco; Sabatino, P.; Carapella, G.; Iemmo, Laura; Schroeder, Thomas; Łupina, Grzegorz

doi:10.1088/0957-4484/26/47/475202

Cited by 92 publications

(78 citation statements)

References 67 publications

(126 reference statements)

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“…The electrical stress increased the graphene–metal coupling and worked to clean the channel. The mobility values are comparable to values already reported for Nb-contacted GFETs [33]. We also noticed that the characteristic measured before the electrical stress showed an asymmetric shape, with the p -branch clearly away from the expected theoretical behavior.…”

Section: Resultssupporting

confidence: 89%

“…We also noticed that the characteristic measured before the electrical stress showed an asymmetric shape, with the p -branch clearly away from the expected theoretical behavior. This can be explained in terms of the reduced coupling between the Nb electrode and the graphene channel (corresponding to large contact resistance), a situation that can cause asymmetry, a double dip, or both in such curves as reported in [33,34]. The improvement of the contact after electrical stress, resulting in better coupling between Nb and graphene, removed the asymmetry.…”

Section: Resultsmentioning

confidence: 81%

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Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

et al. 2016

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We studied the effects of low-energy electron beam irradiation up to 10 keV on graphene-based field effect transistors. We fabricated metallic bilayer electrodes to contact mono- and bi-layer graphene flakes on SiO2, obtaining specific contact resistivity ρc≈19 normalksans-serifΩ·sans-serifµnormalm2 and carrier mobility as high as 4000 cm2·V−1·s−1. By using a highly doped p-Si/SiO2 substrate as the back gate, we analyzed the transport properties of the device and the dependence on the pressure and on the electron bombardment. We demonstrate herein that low energy irradiation is detrimental to the transistor current capability, resulting in an increase in contact resistance and a reduction in carrier mobility, even at electron doses as low as 30 e−/nm2. We also show that irradiated devices recover their pristine state after few repeated electrical measurements.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 81%

Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

et al. 2016

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“…5,[7][8][9] The disadvantage of these methods is, that the conditions under which the mobility is obtained are not the same as for a transistor structure. Alternatively, a commonly accepted experimental method for finding mobility values by direct measurements on G-FETs is to fit a simplified expression for the drain resistance to drain resistance--gate voltage characteristics [10][11][12][13][14] R ¼ R c þ ðL=WÞðqlÞ À1 ððn 0 2 0 þ ðCðV g À V Dirac Þ=qÞ 2 Þ À1=2 :…”

Section: Introductionmentioning

confidence: 99%

Effect of oxide traps on channel transport characteristics in graphene field effect transistors

Bonmann

Vorobiev

Stake

et al. 2017

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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A semiempirical model describing the influence of interface states on characteristics of gate capacitance and drain resistance versus gate voltage of top gated graphene field effect transistors is presented. By fitting our model to measurements of capacitance–voltage characteristics and relating the applied gate voltage to the Fermi level position, the interface state density is found. Knowing the interface state density allows us to fit our model to measured drain resistance–gate voltage characteristics. The extracted values of mobility and residual charge carrier concentration are compared with corresponding results from a commonly accepted model which neglects the effect of interface states. The authors show that mobility and residual charge carrier concentration differ significantly, if interface states are neglected. Furthermore, our approach allows us to investigate in detail how uncertainties in material parameters like the Fermi velocity and contact resistance influence the extracted values of interface state density, mobility, and residual charge carrier concentration.

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“…According to the theoretical prediction [55] for graphene based field effect transistors [56][57][58][59][60], in presence of a wedge tip, enhanced local electrical field can sensibly increase the probability of electron field emission from graphene towards top gate depending on the channel current.…”

Section: Field Emission Propertiesmentioning

confidence: 99%

Transport and field emission properties of buckypapers obtained from aligned carbon nanotubes

Giubileo¹,

Iemmo

Luongo

et al. 2017

J Mater Sci

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We produce 120-µm-thick buckypapers from aligned carbon nanotubes. Transport characteristics evidence ohmic behavior in a wide temperature range nonlinearity appearing in the current–voltage curves only close to 4.2 K. The temperature dependence of the conductance shows that transport is mostly due to thermal fluctuation-induced tunneling, although to explain the whole temperature range from 4.2 to 430 K a further linear contribution is necessary. The field emission properties are measured by means of a nano-controlled metallic tip acting as collector electrode to access local information about buckypaper properties from areas as small as 1 µm2. Emitted current up to 10−5 A and turn-on field of about 140 V/µm are recorded. Long operation, stability and robustness of emitters have been probed by field emission intensity monitoring for more than 12 h at pressure of 10−6 mbar. Finally, no tuning of the emitted current was observed for in-plane applied currents in the buckypaper

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Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics

Cited by 92 publications

References 67 publications

Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

Effect of oxide traps on channel transport characteristics in graphene field effect transistors

Transport and field emission properties of buckypapers obtained from aligned carbon nanotubes

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