Search results

1

Raman modes in transferred bilayer CVD graphene

100%

Niilisk A., Kahro T., Kiisk V., Rähn M., Alles H., Aarik J., Sammelselg V.

Open Physics

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2015

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vol. 13

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issue 1

EN

A systematic experimental Raman spectroscopic study of twisted bilayer graphene (tBLG) domains localized inside wide-area single layer graphene (SLG) produced by low-pressure CVD on Cu foil and transferred onto SiO2/Si substrate has been performed. According to the Raman characterization the tBLG domains had a great variety of twisting angles θ between the bottom and top graphene layers (6° < θ < 25°). The twisting angle θ was estimated from the spectral position of the rotating R and R' modes in the Raman spectrum.Under G band resonance conditions the breathing mode ZO' with a frequency of 95- 97 cm−1 was detected, and a breathing mode ZO was found in the spectra between 804 cm−1 and 836 cm−1, its position depending on the twisting angle θ. An almost linear relationship was found between the frequencies ωZO and ωR. Also a few other spectral peculiarities were found, e.g. a high-energy excitation of the G band resonance, the 2G overtone appearing at 3170-3180 cm−1 by the G band resonance, revealing a linear dispersion of 80 cm−1/eV of the 2D band in tBLG

2

Extraordinary magnetoresistance: sensing the future

100%

Hewett T., Kusmartsev F.

Open Physics

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2012

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vol. 10

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issue 3

602-608

EN

Simulations utilising the finite element method (FEM) have been produced in order to investigate aspects of circular extraordinary magnetoresistance (EMR) devices. The effect of three specific features on the resultant magnetoresistance were investigated: the ratio of the metallic to semiconducting conductivities (σ M/σ S); the semiconductor mobility; and the introduction of an intermediate region at the semiconductormetal interface in order to simulate a contact resistance. In order to obtain a large EMR effect the conductivity ratio (σ M/σ S) is required to be larger than two orders of magnitude; below this critical value the resultant magnetoresistance effect is dramatically reduced. Large mobility semiconductors exhibit larger EMR values for a given field (below saturation) and reduce the magnetic field required to produce saturation of the magnetoresistance. This is due to a larger Hall angle produced at a given magnetic field and is consistent with the mechanism of the EMR effect. Since practical magnetic field sensors are required to operate at low magnetic fields, high mobility semiconductors are required in the production of more sensitive EMR sensors. The formation of a Schottky barrier at the semiconductor-metal interface has been modelled with the introduction of a contact resistance at the semiconductor-metal interface. Increasing values of contact resistance are found to reduce the EMR effect with it disappearing altogether for large values. This has been shown explicitly by looking at the current flow in the system and is consistent with the mechanism of the EMR effect. The interface resistance was used to fit the simulated model to existing experimental data. The best fit occurred with an interface with resistivity of 1.55×10−4 m (overestimate). The EMR effect holds great potential with regard to its future application to magnetic field sensors. The design of any such devices should incorporate high mobility materials (such as graphene) along with the specific features presented in this paper in order to produce effective magnetic field sensors.

3

CPT symmetry in honeycomb lattices and quantum brachistochrone problem

100%

Yeşiltaş Ö.

Open Physics

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2013

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vol. 11

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issue 12

1674-1679

EN

In this paper, we have provided a matrix Hamiltonian model for honeycomb lattices and subsequently obtained the dispersion relation. Furthermore, we have constructed the C operator for the given non-Hermitian Hamiltonian model. The quadratic surfaces are sketched and the quantum Brachistochrone problem is discussed for the given honeycomb lattice model.

4

Effect of Sample Thickness on Carbon Ejection from Ultrathin Graphite Bombarded by keV C_{60}

100%

Golunski M., Postawa Z.

Acta Physica Polonica A

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2017

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vol. 132

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issue 2

222-224

EN

Molecular dynamics computer simulations are employed to investigate the effect of a sample thickness on the ejection process from ultrathin graphite. The thickness of graphite varies from 2 to 16 graphene layers and the system is bombarded by 10 keV C₆₀ projectiles at normal incidence. The ejection yield and the kinetic energy of emitted atoms are monitored. The implications of the results to a novel analytical approach in secondary ion mass spectrometry based on the ultrathin free-standing graphene substrates and transmission geometry are discussed.

5

Remarks on theoretical modelling of spin-dependent electronic transport in carbon nanotubes and graphene

100%

Krompiewski S.

Open Physics

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2011

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vol. 9

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issue 2

369-371

EN

This contribution reports on charge and spin transport through graphene nanoribbons (GrNs) and carbon nanotubes (CNTs). The paper focuses on the giant magnetoresistance effect in these materials, and their potential usefulness for spintronic applications. As examples, the following devices are shortly discussed: GrNs in the ballistic transport regime, a CNT-based Schottky-barrier field effect transistor (CNT SB-FET), as well as CNT quantum dots in the Coulomb blockade limit.

6

Atomic layer deposition of HfO2 on graphene from HfCl4 and H2O

100%

Alles H., Aarik J., Aidla A., Fay A., Kozlova J., Niilisk A., Pärs M., Rähn M., Wiesner M., Hakonen P., Sammelselg V.

Open Physics

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2011

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vol. 9

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issue 2

319-324

EN

Atomic layer deposition of HfO2 on unmodified graphene from HfCl4 and H2O was investigated. Surface RMS roughness down to 0.5 nm was obtained for amorphous, 30 nm thick hafnia film grown at 180°C. HfO2 was also deposited in a two-step temperature process where the initial growth of about 1 nm at 170°C was continued up to 10–30 nm at 300°C. This process yielded uniform, monoclinic HfO2 films with RMS roughness of 1.7 nm for 10–12 nm thick films and 2.5 nm for 30 nm thick films. Raman spectroscopy studies revealed that the deposition process caused compressive biaxial strain in graphene, whereas no extra defects were generated. An 11 nm thick HfO2 film deposited onto bilayer graphene reduced the electron mobility by less than 10% at the Dirac point and by 30–40% far away from it.

7

Laser scribing on HOPG for graphene stamp printing on silicon wafer

100%

Butikova J., Polyakov B., Dimitrocenko L., Butanovs E., Tale I.

Open Physics

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2013

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vol. 11

|

issue 5

580-583

EN

Highly oriented pyrolytic graphite (HOPG) was scribed by pulsed laser beam to produce square patterns. Patterning of HOPG surface facilitates the detachment of graphene layers during contact printing. Direct HOPG-to-substrate and glue-assisted stamp printing of a few-layers graphene was compared. Printed graphene sheets were visualized by optical and scanning electron microscopy. The number of graphene layers was measured by atomic force microscopy. Glue-assisted stamp printing allows printing relatively large graphene sheets (40×40 μm) onto a silicon wafer. The presented method is easier to implement and is more flexible than the majority of existing ways of placing graphene sheets onto a substrate.

8

Predictive modeling and machining performance optimization during drilling of polymer nanocomposites reinforced by graphene oxide/carbon fiber

89%

Jogendra K., Verma R. K., Mondal A. K., Jogendra K., Verma R. K., Mondal A. K.

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vol. 67

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issue 2

9

Nanocomposites graphene/CoFe2O4 and graphene/NiFe2O4 – preparation and characterization

88%

Jędrzejewska A., Sibera D., Pełech R., Jędrzejewski R., Narkiewicz U.

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issue 1

10

Epitaxial graphene perfection vs. SiC substrate quality

88%

Teklinska D., Kosciewicz K., Grodecki K., Tokarczyk M., Kowalski G., Strupinski W., Olszyna A., Baranowski J.

Open Physics

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2011

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vol. 9

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issue 2

446-453

EN

Polytype instability of SiC epitaxial films was the main focus of attention in the experiment performed since this factor has a decisive influence on graphene growth, which was the second stage of the experiment. Layers deposited in various initial C/Si ratios were analyzed. Our observations indicate that the initial C/Si ratio in epitaxial growth is a crucial parameter determining which polytype will be grown, in particular for cubic (3C) or hexagonal (4H) polytypes. If the initial C/Si ratio was close to its final value, the dominant polytype was 4H. On the other hand, when the initial C/Si ratio was close to zero, 3C became the major polytype in spite of a non favourable growth temperature. The results for graphene growth on an epi-SiC layer and a bulk substrate, in which case the dominant polytype was 4H, are also presented. These results indicate that layers on epitaxial 4H-SiC are thicker, more relaxed and have better quality in comparison with samples on 4H-SiC substrates. Morphology and defects in SiC epilayers were analyzed using Nomarsky optical microscopy, scanning electron microscopy (SEM) and high resolution X-ray diffraction (XRD). Graphene quality was characterized by Raman spectroscopy.

11

Graphene crystal growth by thermal precipitation of focused ion beam induced deposition of carbon precursor via patterned-iron thin layers

88%

Rius G., Perez-Murano F., Yoshimura M.

Nanofabrication

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2014

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vol. 1

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issue 1

EN

Recently, relevant advances on graphene as a building block of integrated circuits (ICs) have been demonstrated. Graphene growth and device fabrication related processing has been steadily and intensively powered due to commercial interest; however, there are many challenges associated with the incorporation of graphene into commercial applications which includes challenges associated with the synthesis of this material. Specifically, the controlled deposition of single layer large single crystal graphene on arbitrary supports, is particularly challenging. Previously, we have reported the first demonstration of the transformation of focused ion beam induced deposition of carbon (FIBID-C) into patterned graphitic layers by metal-assisted thermal treatment (Ni foils). In this present work, we continue exploiting the FIBID-C approach as a route for graphene deposition. Here, thin patterned Fe layers are used for the catalysis of graphenization and graphitization. We demonstrate the formation of high quality single and few layer graphene, which evidences, the possibility of using Fe as a catalyst for graphene deposition. The mechanism is understood as the minute precipitation of atomic carbon after supersaturation of some iron carbides formed under a high temperature treatment. As a consequence of the complete wetting of FIBID-C and patterned Fe layers, which enable graphene growth, the as-deposited patterns do not preserve their original shape after the thermal treatment

12

APPLICATIONS OF CHITOSAN–GRAPHENE OXIDE NANOCOMPOSITES IN MEDICAL SCIENCE: A REVIEW

88%

Pieklarz K., Tylman M., Modrzejewska Z.

Progress on Chemistry and Application of Chitin and its Derivatives

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2018

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vol. 23

5-24

EN

Combinations of biopolymers with nanostructured carbon materials have been the subject of interest of many scientists in recent years. Particularly significant are nanocomposites made of chitosan, which is a linear aminopolysaccharide obtained in the process of deacetylation of chitin, and graphene oxide (GO). These systems, due to the atypical properties of both components such as non-toxicity, biocompatibility with human tissues and organs as well as bacteriostaticity, are characterised by a wide range of biomedical applications. They may be used in emergency medicine as dressing materials which accelerate wound healing, as well as carriers of drugs/genes and biological macromolecules, for example proteins, peptides and nucleic acids. In addition, CS-GO systems can potentially be used in regenerative medicine as scaffolds for cell culture. For this reason, the current publication presents the possibilities of the application of chitosan–graphene oxide nanocomposites in medicine considering the characteristics of the system components.

13

Graphene-based Current Mode Logic Circuits: a Simulation Study for an Emerging Technology

88%

Abdollahi H., Hooshmand R., Owlia H.

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issue 3

14

Noise Properties of Graphene-Polymer Thick-Film Resistors

88%

Mleczko K., Ptak P., Zawiślak Z., Słoma M., Jakubowska M., Kolek A.

Metrology and Measurement Systems

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2017

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vol. 24

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issue 4

15

Miniaturized sample preparation based on carbon nanostructures

75%

Cárdenas S.

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issue 1

EN

The evolution of analytical methodologies has been driven by the objective to reduce the complexity of sample treatment while increasing the efficiency of the overall analytical process. For this reason, the analytical chemist takes into consideration advances in other scientific areas and systematically evaluates the potential influence that such discoveries might have on its own discipline. This is the present situation with nanostructured materials, which have already been recognized as a revolution in many scientific and technological fields, including analytical chemistry. Carbon nanoparticles have been a cornerstone in the advance of miniaturization of analytical processes. This review article considers the contribution of four reference carbon nanoparticles: nanotubes, graphene, nanohorns/ cones and fullerenes, in the context of miniaturized sample treatment, where their outstanding sorbent properties are by far the most exploited in (micro) solid phase extraction.

16

Investigation on Mechanical Properties and Microstructures of Aluminum Hybrid Composites Reinforced with Al2O3/GNPs Binary Particles

75%

Can Şenel M., Gürbüz M., Can Şenel M., Gürbüz M.

Archives of Metallurgy and Materials

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2021

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vol. 66

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issue 1

17

Investigating Sintering Behavior of the Graphene Nanoplatelets (GNPs) Reinforced Aluminum Nanocomposites Via Low Energy Solution Ball Milling

75%

Baig Z., Mamat O., Mustapha M., Ali S., Baig Z., Mamat O., Mustapha M., Ali S.

Archives of Metallurgy and Materials

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2020

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vol. 65

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issue 2

18

Graphene-Based Composite Membrane for Water Desalination

75%

Dybowski K., Kowalczyk P., Kula P., Jeziorna A., Atraszkiewicz R., Kołodziejczyk Ł., Zawadzki P., Nowak D., Kazimierczak T., Kucińska M.

Archives of Metallurgy and Materials

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2018

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vol. 63

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issue 3

19

Impact of the Method of Separating Graphene from the Growth Substrate on the Quality of the 2D Material Obtained

75%

Dybowski K., Romaniak G., Kula P., Jeziorna A., Kowalczyk P., Atraszkiewicz R., Kołodziejczyk Ł., Nowak D., Zawadzki P., Kucińska M., Dybowski K., Romaniak G., Kula P., Jeziorna A., Kowalczyk P., Atraszkiewicz R., Kołodziejczyk Ł., Nowak D., Zawadzki P., Kucińska M.

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issue 4

20

Aluminum Metal Matrix Composites with SiC, Al2O3 and Graphene – Review

75%

Aybarc U., Dispinar D., Seydibeyoglu M. O.

Archives of Foundry Engineering

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2018

|

issue 2

Refine search results

Raman modes in transferred bilayer CVD graphene

Extraordinary magnetoresistance: sensing the future

CPT symmetry in honeycomb lattices and quantum brachistochrone problem

Effect of Sample Thickness on Carbon Ejection from Ultrathin Graphite Bombarded by keV C_{60}

Remarks on theoretical modelling of spin-dependent electronic transport in carbon nanotubes and graphene

Atomic layer deposition of HfO2 on graphene from HfCl4 and H2O

Laser scribing on HOPG for graphene stamp printing on silicon wafer

Predictive modeling and machining performance optimization during drilling of polymer nanocomposites reinforced by graphene oxide/carbon fiber

Nanocomposites graphene/CoFe2O4 and graphene/NiFe2O4 – preparation and characterization

Epitaxial graphene perfection vs. SiC substrate quality

Graphene crystal growth by thermal precipitation of focused ion beam induced deposition of carbon precursor via patterned-iron thin layers

APPLICATIONS OF CHITOSAN–GRAPHENE OXIDE NANOCOMPOSITES IN MEDICAL SCIENCE: A REVIEW

Graphene-based Current Mode Logic Circuits: a Simulation Study for an Emerging Technology

Noise Properties of Graphene-Polymer Thick-Film Resistors

Miniaturized sample preparation based on carbon nanostructures

Investigation on Mechanical Properties and Microstructures of Aluminum Hybrid Composites Reinforced with Al2O3/GNPs Binary Particles

Investigating Sintering Behavior of the Graphene Nanoplatelets (GNPs) Reinforced Aluminum Nanocomposites Via Low Energy Solution Ball Milling

Graphene-Based Composite Membrane for Water Desalination

Impact of the Method of Separating Graphene from the Growth Substrate on the Quality of the 2D Material Obtained

Aluminum Metal Matrix Composites with SiC, Al2O3 and Graphene – Review