Charge transfer and partial pinning at the contacts as the origin of a double dip in the transfer characteristics of graphene-based field-effect transistors

We fabricate back-gated field effect transistors using Niobium electrodes on mechanically exfoliated monolayer graphene and perform electrical characterization in the pressure range from atmospheric down to 10 -4 mbar. We study the effect of room temperature vacuum degassing and report asymmetric transfer characteristics with a resistance plateau in the n-branch. We show that weakly chemisorbed Nb acts as p-dopant on graphene and explain the transistor characteristics by Nb/graphene interaction with unpinned Fermi level at the interface.

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“…If the Fermi level is not pinned, the gate voltage is able to further tune the charge density of graphene in the contact region [53][54]. [43].…”

Section: Resultsmentioning

confidence: 99%

Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics

et al. 2015

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“…A positive charge that is trapped at the graphene/oxide interface in the vicinity of the drain has induced the formation of a p-n junction in the drain region resulting in sharp and distinct Dirac points. [ 11,18 ] [ 57 ] A second feature observed in their I d -V gs curves is a clear hysteresis between the forward and reverse sweeps of the gate voltage. In this work, we deposited an ultrathin layer of PEIE (10 nm thick) and observed two distinct Dirac points without any appearance of hysteresis or a need for electrical cycling.…”

Section: Electrical Data Measurementsmentioning

confidence: 99%

Formation of Air Stable Graphene p–n–p Junctions Using an Amine‐Containing Polymer Coating

Sojoudi

Baltazar

Tolbert

et al. 2014

Adv Materials Inter

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An ultrathin layer of a polymer containing simple aliphatic amine groups, polyethylenimine ethoxylated (PEIE), is deposited on a back‐gated field effect graphene device to form graphene p–n–p junctions. Characteristic I–V curves indicate the superposition of two separate Dirac points, which confirms an energy separation of neutrality points within the complementary regions. This is a simple approach for making graphene p–n–p junctions without a need for multiple lithography steps or electrostatic gates and, unlike, the destructive techniques such as substitutional doping or covalent functionalization, it induces a minor defect, if any, as there is no discernible D peak in the Raman spectra of the graphene films after creating junctions and degradation in the charge carrier mobilities of the graphene devices. This method can be easily processed from dilute solutions in environmentally‐friendly solvents such as water or methoxyethanol and does not suffer any change upon exposure to air or heating at temperatures below 100 °C.

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“…Antonio et al [70] ascribed double dip in I ds − V bg to charge transfer between the graphene and the metal electrodes. Nouchi et al [71] have also reported that anomalously distorted transportation originated from the partially formed oxide layer in Ni/graphene contact.…”

Section: Interface Impactmentioning

confidence: 99%

A Study on Graphene—Metal Contact

et al. 2013

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Charge transfer and partial pinning at the contacts as the origin of a double dip in the transfer characteristics of graphene-based field-effect transistors

Cited by 72 publications

References 38 publications

Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics

Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics

Formation of Air Stable Graphene p–n–p Junctions Using an Amine‐Containing Polymer Coating

A Study on Graphene—Metal Contact

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