| 1. |
- Svensson, Johannes, 1978, et al.
(författare)
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Carbon Nanotube Diameter Dependence of the Schottky Barrier Height for Pd – Carbon Nanotube Contacts
- 2009
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 20:17
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Tidskriftsartikel (refereegranskat)abstract
- Direct measurements are presented of the Schottky barrier (SB) heights of carbon nanotube devices contacted with Pd electrodes. The SB barrier heights were determined from the activation energy of the temperature-dependent thermionic emission current in the off-state of the devices. The barrier heights generally decrease with increasing diameter of the nanotubes and they are in agreement with the values expected when assuming little or no influence of Fermi level pinning.
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| 2. |
- Baek, S. J., et al.
(författare)
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Electrical conduction of palladium-decorated multi-layered graphene oxide effected by hydrogen dissociation
- 2015
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Ingår i: Synthetic Metals. - : Elsevier BV. - 0379-6779. ; 199, s. 74-78
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Tidskriftsartikel (refereegranskat)abstract
- Multi-layered graphene oxide (MGO) and palladium-decorated MGO (PdGO) are electrically evaluated as a function of H-2 pressure up to 20 bar to elucidate an interaction between molecular hydrogen and PdGO. As H-2 pressure increases, the electrical conductance (G) of MGO also increases while that of PdGO decreases. Using atomic force microscopy, X-ray photoelectron spectroscopy, and Fourier transform-infrared spectroscopy analysis, we found that MGO reduction due to H-2 accounts for the increase in G of the MGO. For PdGO, an increase of OH groups was observed, which shows that PdGO was oxidized when exposed to high H-2 pressure. The PdGO oxidation can be explained by a hydrogen spillover effect and the decrease of G may be due to this behavior.
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| 3. |
- He, Hans, 1989, et al.
(författare)
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Uniform doping of graphene close to the Dirac point by polymer-assisted assembly of molecular dopants
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Tuning the charge carrier density of two-dimensional (2D) materials by incorporating dopants into the crystal lattice is a challenging task. An attractive alternative is the surface transfer doping by adsorption of molecules on 2D crystals, which can lead to ordered molecular arrays. However, such systems, demonstrated in ultra-high vacuum conditions (UHV), are often unstable in ambient conditions. Here we show that air-stable doping of epitaxial graphene on SiC—achieved by spin-coating deposition of 2,3,5,6-tetrafluoro-tetracyano-quino-dimethane (F4TCNQ) incorporated in poly(methyl-methacrylate)—proceeds via the spontaneous accumulation of dopants at the graphene-polymer interface and by the formation of a charge-transfer complex that yields low-disorder, charge-neutral, large-area graphene with carrier mobilities ~70 000 cm2V−1s−1at cryogenic temperatures. The assembly of dopants on 2D materials assisted by a polymer matrix, demonstrated by spin-coating wafer-scale substrates in ambient conditions, opens up a scalable technological route toward expanding the functionality of 2D materials.
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| 4. |
- Hong, S. J., et al.
(författare)
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Verification of electron doping in single-layer graphene due to H-2 exposure with thermoelectric power
- 2015
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 106:14
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Tidskriftsartikel (refereegranskat)abstract
- We report the electron doping of single-layer graphene (SLG) grown by chemical vapor deposition (CVD) by means of dissociative hydrogen adsorption. The transfer characteristic showed n-type doping behavior similar to that of mechanically exfoliated graphene. Furthermore, we studied the thermoelectric power (TEP) of CVD-grown SLG before and after exposure to high-pressure H-2 molecules. From the TEP results, which indicate the intrinsic electrical properties, we observed that the CVD-grown SLG is n-type doped without degradation of the quality after hydrogen adsorption. Finally, the electron doping was also verified by Raman spectroscopy.
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| 5. |
- Kim, B., et al.
(författare)
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Electrical transport measurement of molecular device fabricated by electrochemical deposition of platinum electrode
- 2006
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 499, s. 196-200
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Tidskriftsartikel (refereegranskat)abstract
- Electrical properties of 1,4-benzenedimethanethiol are measured using the electrochemically deposited platinum electrode as one of contact lead to the molecule. Temperature dependence of current-voltage characteristics were measured from room temperature to 27 K. Fowler–Nordheim type tunneling conduction below 40 K and current fluctuation at low temperature were observed. The fluctuating behavior can be understood as electromigration and/or thermal vibration of platinum atoms at the contact between the molecule and the platinum electrode.
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| 6. |
- Kim, Kyung Ho, 1984, et al.
(författare)
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Apparent Power Law Scaling of Variable Range Hopping Conduction in Carbonized Polymer Nanofibers
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- We induce dramatic changes in the structure of conducting polymer nanofibers by carbonization at 800 degrees C and compare charge transport properties between carbonized and pristine nanofibers. Despite the profound structural differences, both types of systems display power law dependence of current with voltage and temperature, and all measurements can be scaled into a single universal curve. We analyze our experimental data in the framework of variable range hopping and argue that this mechanism can explain transport properties of pristine polymer nanofibers as well.
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| 7. |
- Kim, Kyung Ho, 1984, et al.
(författare)
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Thermal stability of epitaxial graphene electrodes for conductive polymer nanofiber devices
- 2017
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Ingår i: Crystals. - : MDPI AG. - 2073-4352. ; 7:12
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Tidskriftsartikel (refereegranskat)abstract
- We used large area, monolayer graphene epitaxially grown on SiC (0001) as contact electrodes for polymer nanofiber devices. Our fabrication process, which avoids polymer resist residues on the graphene surface, results in graphene-polyaniline nanofiber devices with Ohmic contacts and electrical conductivity comparable to that of Au-nanofiber devices. We further checked the thermal stability of the graphene contacts to polyaniline devices by annealing up to T = 800 °C, the temperature at which polyaniline nanofibers are carbonized but the graphene electrode remains intact. The thermal stability and Ohmic contact of polymer nanofibers are demonstrated here, which together with the chemical stability and atomic flatness of graphene, make epitaxial graphene on SiC an attractive contact material for future all-carbon electronic devices.
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| 8. |
- Kulinich, Sergeij I., et al.
(författare)
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Nanomechanics of a magnetic shuttle device
- 2014
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Ingår i: Low temperature physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 40:10, s. 1161-1169
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Tidskriftsartikel (refereegranskat)abstract
- We show that self sustained mechanical vibrations in a model magnetic shuttle device can be driven by both the charge and the spin accumulated on the movable central island of the device. Different scenarios for how spin- and charge-induced shuttle instabilities may develop are discussed and shown to depend on whether there is a Coulomb blockade of tunneling or not. The crucial role of electronic spin flips in a magnetically driven shuttle is established and shown to cause giant magnetoresistance and dynamic magnetostriction effects.
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| 9. |
- Lee, SangWook, et al.
(författare)
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Fabrication and mechanical properties of suspended one-dimensional polymer nanostructures: polypyrrole nanotube and helical polyacetylene nanofibre
- 2006
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 17, s. 992-996
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical properties of suspended quasi-one-dimensional polymer nanostructures were investigated using atomic force microscopy (AFM). A recently developed new acid-free etch method combined with electron beam lithography was used to fabricate suspended polypyrrole (PPy) nanotubes and helical polyacetylene (HPA) nanofibres. The elastic modulus of each suspended structure was obtained by AFM force–distance measurements. The estimated modulus value of the PPy nanotube (HPA nanofibre) was 0.96 GPa (0.5 GPa). Using this acid-free method, all-organic flexible NEMS devices can be fabricated in the future.
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| 10. |
- Nam, Youngwoo, 1983, et al.
(författare)
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Quantum Hall effect in graphene decorated with disordered multilayer patches
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:233, s. 233110-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum Hall effect (QHE) is observed in graphene grown by chemical vapour deposition using platinum catalyst. The QHE is even seen in samples which are irregularly decorated with disordered multilayer graphene patches and have very low mobility (
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