| 1. |
- Fu, Yifeng, 1984, et al.
(författare)
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Templated Growth of Covalently Bonded Three-Dimensional Carbon Nanotube Networks Originated from Graphene
- 2012
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 24:12, s. 1576-1581
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Tidskriftsartikel (refereegranskat)abstract
- A template-assisted method that enables the growth of covalently bonded three-dimensional carbon nanotubes (CNTs) originating from graphene at a large scale is demonstrated. Atomic force microscopy-based mechanical tests show that the covalently bonded CNT structure can effectively distribute external loading throughout the network to improve the mechanical strength of the material.
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| 2. |
- Lindvall, Niclas, 1985, et al.
(författare)
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Towards transfer-free fabrication of graphene NEMS grown by chemical vapour deposition
- 2012
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Ingår i: Micro and Nano Letters. - : Institution of Engineering and Technology (IET). - 1750-0443. ; 7:8, s. 749-752
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Tidskriftsartikel (refereegranskat)abstract
- Graphene, an atomic monolayer of sp(2)-hybridised carbon atoms, is a promising material for future NEMS based on its remarkable electronic and mechanical properties. Through the rapid progress of chemical vapour deposition of large-scale, high-quality graphene, these applications seem to be close to reality. However, issues related to the graphene transfer process limit the reproducibility of such devices. In this Letter, the authors present two different approaches for fabricating suspended graphene devices without any transfer step, using both catalytically and non-catalytically grown graphene. The authors achieve high reproducibility in manufacturing flat and uniform suspended graphene beams. While good mechanical properties are observed, the electrical performance is still poor, requiring improvements.
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| 3. |
- Lindvall, Niclas, 1985, et al.
(författare)
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Transfer-free fabrication of suspended graphene grown by chemical vapor deposition
- 2012
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Ingår i: 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems. NEMS 2012, Kyoto, 5 - 8 March 2012. - 9781467311243 ; , s. 19-22
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Konferensbidrag (refereegranskat)abstract
- Graphene, a true two-dimensional material with extraordinary mechanical- and electronic properties, is thought to be ideal for nanoelectromechanical systems (NEMS), like mass- and force sensors. Here, we present two different ways to fabricate suspended graphene for the intended use in future NEMS applications. The fabrication schemes do not require transfer of graphene from a catalyst where the graphene is grown on to another supporting substrate. The transfer is a source of several issues causing irreproducibility in large-scale production of graphene devices. We obtain suspended graphene membranes by locally removing the copper thin film on top of which the graphene is catalytically grown. The membranes are uniform and exhibit mechanical properties similar to those of exfoliated graphene. Also, suspended graphene beams with electrical interconnects are fabricated from non-catalytically grown graphene on SiO 2. Both approaches represent the first steps towards transfer-free fabrication of suspended graphene for NEMS applications.
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| 4. |
- Lockhart de la Rosa, César Javier, 1987, et al.
(författare)
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Frame assisted H2O electrolysis induced H2 bubbling transfer of large area graphene grown by chemical vapor deposition on Cu
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:2
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Tidskriftsartikel (refereegranskat)abstract
- An improved technique for transferring large area graphene grown by chemical vapor deposition on copper is presented. It is based on mechanical separation of the graphene/copper by H-2 bubbles during H2O electrolysis, which only takes a few tens of seconds while leaving the copper cathode intact. A semi-rigid plastic frame in combination with thin polymer layer span on graphene gives a convenient way of handling-and avoiding wrinkles and holes in graphene. Optical and electrical characterizations prove the graphene quality is better than that obtained by traditional wet etching transfer. This technique appears to be highly reproducible and cost efficient.
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| 5. |
- Nam, Youngwoo, 1983, et al.
(författare)
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Graphene p-n-p junctions controlled by local gates made of naturally oxidized thin aluminium films
- 2012
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 50:5, s. 1987-1992
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Tidskriftsartikel (refereegranskat)abstract
- Graphene structures with both top- and bottom-electrostatic gates are studied. The top gate is made of thin aluminium (Al) film deposited directly onto graphene, with no prior dielectric layer in between. Natural oxidation of Al at the interface with graphene results in an insulating barrier proving useful in making top gates to graphene. For electrically disconnected top gate, graphene resistance as a function of the slowly-varying back-gate voltage shows hysteresis which reveals dielectric properties of the barrier. The estimated barrier thickness is only 2 nm allowing for very sharp profiles of the electric field in graphene devices. By applying voltages to both back- and top gates, effective p–n–p junctions with sharp interfaces can be created.
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| 6. |
- 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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| 7. |
- Nam, Youngwoo, 1983, et al.
(författare)
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Unusual thermopower of inhomogeneous graphene grown by chemical vapor deposition
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 104:2, s. 021902 -
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Tidskriftsartikel (refereegranskat)abstract
- We report on thermopower (TEP) and resistance measurements of inhomogeneous graphene grown by chemical vapor deposition (CVD). Unlike the conventional resistance of pristine graphene, the gate-dependent TEP shows a large electron-hole asymmetry. This can be accounted for by inhomogeneity of the CVD-graphene where individual graphene regions contribute with different TEPs. At the high magnetic field and low temperature, the TEP has large fluctuations near the Dirac point associated with the disorder in the CVD-graphene. TEP measurements reveal additional characteristics of CVD-graphene, which are difficult to obtain from the measurement of resistance alone.
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| 8. |
- Sellappan, Raja, 1981, et al.
(författare)
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Influence of graphene synthesizing techniques on the photocatalytic performance of Graphene/TiO2 nanocomposites
- 2013
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Ingår i: Physical Chemistry Chemical Physics. - 1463-9084 .- 1463-9076. ; 15:37, s. 15528-15537
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Tidskriftsartikel (refereegranskat)abstract
- Model photocatalysts composed of TiO2/graphene nanocomposites are prepared to address the role of graphene quality on their photocatalytic performance. Graphene is synthesized by catalyst-assisted chemical vapor deposition (CVD), catalyst-free CVD and solution processing methods. TiO2 is prepared by reactive magnetron sputtering and subsequent annealing. Fabricated model photocatalysts are with different morphology and physical properties, as revealed by spectrophotometry, atomic force microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, photoluminescence, and four-probe electrical measurements. All graphene–containing composites are with significantly higher photocatalytic activity compared to bare TiO2 films in the gas phase methanol photooxidation tests. The activity is proportional to the electrical conductivity and surface roughness of the respective carbon structure, which in turn depends on the preparation methods. The mechanisms of enhancement are further assessed by comparison with the performance of reference TiO2/graphitic-carbon and TiO2/Au thin films.
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| 9. |
- Skoblin, Grigory, 1991, et al.
(författare)
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A hybrid-type CVD system for graphene growth
- 2015
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Ingår i: Chemical Vapor Deposition. - : Wiley. - 1521-3862 .- 0948-1907. ; 21:7-9, s. 176-180
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Tidskriftsartikel (refereegranskat)abstract
- A cold-wall CVD system for graphene growth on metal foils is converted to an effectively hot-wall one by merely adding another heater, sandwiching the foil in between the heaters. This simple design demonstrates both an improved temperature uniformity characteristic for hot-wall systems, and a high responsivity distinctive for cold-wall ones. This beneficial combination allows for a much better control of graphene growth kinetics. An effectively hot-wall system for graphene growth is made from a cold-wall one by encapsulating the metal foil in between two heaters. This simple conversion demonstrates improved temperature control and high temperature ramping rate. It also allows reaching lower nucleation density and provides better control of growth kinetics.
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| 10. |
- Sun, Jie, 1977, et al.
(författare)
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Chemical vapor deposition of nanocrystalline graphene directly on arbitrary high-temperature insulating substrates
- 2012
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Ingår i: 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems. NEMS 2012, Kyoto, 5 - 8 March 2012. - 9781467311243 ; , s. 11-14
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Konferensbidrag (refereegranskat)abstract
- Large area uniform nanocrystalline graphene is grown by chemical vapor deposition on arbitrary insulating substrates that can survive ∼1000°C. The as-synthesized graphene is nanocrystalline with a domain size in the order of ∼10 nm. The material possesses a transparency and conductivity similar to standard graphene fabricated by exfoliation or catalysis. A noncatalytic mechanism is proposed to explain the experimental phenomena. The developed technique is scalable and reproducible, compatible with the existing semiconductor technology, and thus can be very useful in nanoelectronic applications such as transparent electronics, nanoelectromechanical systems, as well as molecular electronics.
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