The effect of Holstein phonons on the electrical conductivity of doped monolayer graphene

2013 ◽  
Vol 54 ◽  
pp. 202-205 ◽  
Author(s):  
Hamed Rezania
Keyword(s):  
Electrical Conductivity ◽  
Monolayer Graphene

Simple and environment-friendly method for graphene synthesis by using ultrasound.

2021 ◽  
Vol 17 ◽  
Author(s):  
Irena Markovska ◽  
Dimitar Georgiev ◽  
Fila Yovkova ◽  
Miroslav Abrashev
Keyword(s):  
Electrical Conductivity ◽  
Raman Spectroscopy ◽  
Monolayer Graphene ◽  
Conductivity Measurements ◽  
Environment Friendly ◽  
Complex Processes ◽  
Graphene Synthesis ◽  
Pure Graphite ◽  
Ft Ir ◽  
Electrodes For Supercapacitors

Background: This paper proposes a technology for the production of monolayer graphene by an easy, accessible, and non-toxic method. Methods: For the preparation of graphene, a combination of chemical and physical (ultrasonic) treatment of the original graphite precursor (purity >99%) was applied. The precursor of graphite is placed in a beaker with a solution of KOH or H2SO4. The mixtures were homogenized well and sonicated for 4h. The applied ultrasound has a power of 120 W, frequency 40 kHz. Due to the effects of ultrasound, complex processes take place in the solutions, which leads to the formation of superfine graphene. Better results were obtained at samples treated with 2n H2SO4. The physicochemical properties of the resulting graphene were characterized mainly by Raman spectroscopy, FT-IR, TEM, SEM, and electrical conductivity measurements. Results: Our research was focused mainly on the field of nanotechnology, in particular on the synthesis of graphene, which could be used as a coating on electrodes for supercapacitors. In this connection, three series of samples were developed in which the pristine graphite was treated with 2n H2SO4, 4n H2SO4, and 6n H2SO4, respectively, and their electrical properties were measured. Conclusion: The obtained graphene shows electrical resistivity 2-3 times lower than that of the precursor of pure graphite.

scholarly journals Measurements of the Electrical Conductivity of Monolayer Graphene Flakes Using Conductive Atomic Force Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2575
Author(s):  
Soomook Lim ◽  
Hyunsoo Park ◽  
Go Yamamoto ◽  
Changgu Lee ◽  
Ji Won Suk
Keyword(s):  
Electrical Conductivity ◽  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Monolayer Graphene ◽  
Synthesis Methods ◽  
Clear Understanding ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Flakes

The intrinsic electrical conductivity of graphene is one of the key factors affecting the electrical conductance of its assemblies, such as papers, films, powders, and composites. Here, the local electrical conductivity of the individual graphene flakes was investigated using conductive atomic force microscopy (C-AFM). An isolated graphene flake connected to a pre-fabricated electrode was scanned using an electrically biased tip, which generated a current map over the flake area. The current change as a function of the distance between the tip and the electrode was analyzed analytically to estimate the contact resistance as well as the local conductivity of the flake. This method was applied to characterize graphene materials obtained using two representative large-scale synthesis methods. Monolayer graphene flakes synthesized by chemical vapor deposition on copper exhibited an electrical conductivity of 1.46 ± 0.82 × 106 S/m. Reduced graphene oxide (rGO) flakes obtained by thermal annealing of graphene oxide at 300 and 600 °C exhibited electrical conductivities of 2.3 ± 1.0 and 14.6 ± 5.5 S/m, respectively, showing the effect of thermal reduction on the electrical conductivity of rGO flakes. This study demonstrates an alternative method to characterizing the intrinsic electrical conductivity of graphene-based materials, which affords a clear understanding of the local properties of individual graphene flakes.

A Continuous Electrical Conductivity Model for Monolayer Graphene From Near Intrinsic to Far Extrinsic Region

2014 ◽  
Vol 61 (11) ◽  
pp. 3646-3653 ◽  
Author(s):  
Sitangshu Bhattacharya ◽  
Dipankar Saha ◽  
Aveek Bid ◽  
Santanu Mahapatra
Keyword(s):  
Electrical Conductivity ◽  
Monolayer Graphene ◽  
Conductivity Model

scholarly journals Determination of the DC Electrical Conductivity of Multiwalled Carbon Nanotube Films and Graphene Layers from Noncontact Time-Domain Terahertz Measurements

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
E. Dadrasnia ◽  
H. Lamela ◽  
M. B. Kuppam ◽  
F. Garet ◽  
J.-L. Coutaz
Keyword(s):  
Electrical Conductivity ◽  
Time Domain ◽  
Electrical Contact ◽  
Extraction Procedure ◽  
Dc Conductivity ◽  
Monolayer Graphene ◽  
Contact Method ◽  
Multiwalled Carbon ◽  
Graphene Layers ◽  
The One

Measuring the DC conductivity of very thin films could be rather difficult because of the electrical contact issue. This DC conductivity can, however, be extracted from noncontact measurements at GHz and THz frequencies using elaborated conductivity models that nicely fit the experimental data. Here we employ this technique to study the DC conductivity of fragile nanometer-thick films of multiwalled carbon nanotubes and monolayer graphene. The THz response of the films is measured by THz time-domain spectroscopy. We show that the THz conductivity of the samples is well fitted by either Drude-Lorentz model or Drude-Smith model, giving information on the physics of electrical conductivity in these materials. This extraction procedure is validated by the good agreement between the so-obtained DC conductivity and the one measured with a classical 4-point probe in-line contact method.

Regularities of Electrical Conductivity of Monolayer Graphene Nanomesh with Round Holes

2021 ◽  
Vol 23 (5) ◽  
pp. 231-237
Author(s):  
O.E. Glukhova ◽  
◽  
M.M. Slepchenkov ◽  
P.V. Barkov ◽  
◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Energy Gap ◽  
Monolayer Graphene ◽  
Current Transfer ◽  
Neck Width ◽  
Zigzag Direction ◽  
Circular Holes ◽  
Graphene Nanomesh ◽  
Density Of Electron States ◽  
Armchair Direction

This paper studies graphene nanomesh with different neck width is the smallest distance between two neighboring holes. The electrical properties of graphene nanomesh with circular holes were calculated in dependence on its neck width. For the considered structures energetical characteristics including energy gap (Egap), Fermi level (Ef), and density of electron states (DOS) were found. It was established that graphene nanomesh demonstrated both metallic and semiconductor types of conductivity when the neck width was increased along the zigzag direction. In the case of increasing the neck width along armchair direction, graphene nanomesh demonstrated only a metallic type of conductivity. It was observed the anisotropy of electrical conductivity depending on the direction along which the current transfer was carried out.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

1983 ◽  
Vol 41 ◽  
pp. 606-607
Author(s):  
Klaus-Ruediger Peters ◽  
Samuel A. Green
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Critical Point ◽  
Metal Films ◽  
High Magnification ◽  
Osmium Impregnation ◽  
Instrumental Resolution ◽  
20 Nm ◽  
Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

Sign in / Sign up

Export Citation Format

Share Document