Strong Quantum Confinement Effects in Nanometer Devices with Graphene Directly Grown on Insulator by Catalyst-free Chemical Vapor Deposition
Background: The understanding of electrical properties of defective graphene in nanometer
regime has lagged behind.
Objective: This report intends to characterize defective but practically useful graphene as nanometer
Method: A-few-layer-thick graphene was directly grown on SiO2 substrate by alcohol-chemical vapor
deposition (alcohol-CVD) using ethanol as carbon source and without the use of any catalytic metal.
The graphene film was delineated into nanometer structures by electron beam lithography to make the
Results: The Raman spectra of the graphene sheet on SiO2 shows relatively large D peak, which means
the graphene is defective and consists of nanograins with an estimated size of 17 nm. Modulation of the
graphene resistance by the gate voltage Vg was studied at room temperature. The film shows only p-type
conduction, with a sheet resistance of 3.7 kΩ / and field-effect mobility calculated to be 44 cm2/Vs.
From the temperature dependence of the graphene sheet, it is found that the resistance increases only by
7% from room temperature to 10 K, indicating low potential barrier between the domains, even though the
graphene film is as thin as 1.6 nm and defective. From the conductance (Id/Vd) contour plot measured at 10
K of these nanodevices, aperiodic Coulomb-blockade feature and transport with a large gap were observed.
Conclusion: Correlation among narrowest constriction widths, the variation of the addition energies and
transport gaps in disordered graphene nanostructures is evident. These graphene nanodevices may have
promising application in various nanodevices like single-electron (or single-hole) transistor, singlemolecule
transistor, van-der-Waals stacked nanodevices, etc.
Keywords: Graphene nanostructures, Coulomb blockade, graphene nanometer devices, alcohol chemical vapor deposition,
electron beam lithography, Raman spectra, sheet resistance.
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