Graphene Definition and 189 Threads

Hi, Homework Statement I have two questions, in fact, both involving 2D graphene: (1) How may I determine the number of nearest neighbours in a primitive cell of graphene? (2) Given that graphene has linear energy dispersion near the fermi level and the dispersion is given by E=(hbar)vF|k|...

Homework Statement French physics teacher have tried to find out the script of this video but would appreciate the review from a native speaker. Thank you for your help. http://vfsilesieux.free.fr/graphenevideo2/video.swf

Hi everyone, long time lurker, first time poster. I've just begun a phd which involves nanoribbons (a small strip of a 2D material connected at either end to a larger 'bulk' section of the same 2D material). A question has occurred to me. These nanoribbons look a lot like a piece of string...

Hi as an undergrad Physics student learning quantum mechanics for the first time, I'm having a hard time wrapping my head around quantum tunneling, why does it happen, why can it happen? I was also reading that Graphene exhibits tunneling as well, could someone explain this?

Hi, * There is no bandgap for zigzag GNRs if the spin is neglected. In some of the studies in the literature, spin is neglected and analyses are done considering zigzag GNRs as metallic. * In another group of works however, it is argued that spin-polarized bandstructure of zGNRs have small...

Hi, I got a graphene dispersion on ebay but the graphene flakes cumulated at the bottom of the bottle. I'm trying to mix it and then solve in water using an ultrasonic cleaner but the flakes do not dissolve in water? How can I dissolve it so that I can obtain a large scale graphene by...

Hi, I just got a small bottle of graphene dispersion (not GO) on ebay and put a small drop on a ciruit board as shown in the pic. I expected to measure a finite resistance because graphene is a conductor as much as I know. But it seems to have zero conductance from what I read on the...

So lately (meaning the past few years) I've been hearing a lot about graphene and how it's amazing. It's apparently super strong, has a high conductivity and many other amazing properties. It was the subject for which a nobel prize was won, and it supposedly will change the future. I can't...

This amazing study suggests that the material Graphene may make the internet one hundred times faster,here some links http://www.bath.ac.uk/news/2013/07/12/graphene-internet-speed/ http://prl.aps.org/abstract/PRL/v110/i21/e217406 what do you think of it?

What method can be used to make large macro-sized sheets of graphene? There have been recent articles on research showing that patchwork quilts composed of large sections of graphene have nearly the same bulk strength as pure graphene would...

I have been hearing about the possibility of a graphene super capacitor for quite some time now, but it still seems they are not readily available. Is there anyway for me to get my hands on one? Would it be possible for me to buy/make one practical enough to replace a AA battery? What size...

Hi, I'm a 4th-year physics undergrad and I have a question about calculating the band structure of graphene using tight binding. Following the calculation here...

I've read that it's several times stronger than steel. I haven't read anything about its stabbing resistance against the tip of a knife, though. Does anyone have any ideas on this subject? Could a human stab through an inch of it?

I am trying to reproduce Kaner and El-Kadys Graphene based electrochemical capacitors (ECs). The process reduces Graphite-oxide (GO) to laser-scribed graphene (LSG) using a lightscribe. I think I have figured out a way to produce the graphite-oxide from watching a couple of great videos on...

Homework Statement I want to know why Graphene has the properties it has, I am really struggling to find out why graphene has the properties it does. Strength, I know graphene contains covalent bonds which are strong and that it has a hexagonal lattice structure. Electrical conductance I know...

A lot of hype is out there about both of them (especially the latter) and I was wondering if there is more concrete information about them other than the news IBM posted on a circuit 2 years ago and the patent war about Graphene transistors involving Samsung and IBM among others. Also, what's up...

I heard that people envision strong structural materials made out of graphene, but I heard it may weaken when being stack in layers. Is graphene viable for macroworld structural engineering or is it only suitable for electronics and similar applications?

Hello, I was just wondering what the theoretical thickness of single layer graphene is? Thanks in advance for any feedback.

We've been making things out of graphite for ages, which certainly has its uses, but interest in graphene has just started to take off recently. It's hailed as a miracle material and it seems that it was right under our noses all along - how come it took such a long time to be discovered?

everyone knows, there exists the relation between the group velocity and energy dispersion. a question is how to expression the relation between the velocity and momentum k? it seems that the Dirac electron in graphene is massless.

Hi to everyone I'm working on mu thesis with this title: Calculation of graphene conductivity in the semiclassical regime And also I should calculate it with Boltzmann equation Is there anybody who can guide me for where to start and even how to calculate the graphene conductivity using...

I have had a question on my mind for a while now. Would it be possible to make a graphene supercapacitor using the scotch tape method for making graphene? Except unroll the entire roll of tape and cover it in graphite and then press it against another entire roll of scotch tape, peel off and...

Hello- I am trying to find a reference describing the z(or c) component of the basis vectors for graphene. I seem to recall that there is a slight bend such that half of the atoms lie slightly above the plane. However, every paper I have found references the perfect 2D lattice of Graphene...

Hi Everyone, I have recently made some graphene on copper via a chemical vapour deposition process. I have also managed to have a peep under an SEM at this. I do see what I believe to be monolayer graphene. I am very sure the contrast I see is graphene due to the growth patterns, ranging from...

In graphene the fermi level can be moved into the conduction or valence bands by applying an external electric field, allowing conduction by either holes or electrons. My question is where do these new electrons come from (or go to in the p-type case)? Also, why is this special to...

Graphene -- Green's function technique Hi, I am looking for a comprehensive review about using Matsubara Green's function technique for graphene (or at least some hints in the following problem). I have already learned some finite temperature Green's function technique, but only the basics...

Hello! I am a student and have just started studying about graphene. However I am having quite a lot of problems understanding the crystal structure, specifically, I am unable to place certain terms. These being : 1. Basis vectors.(I do understand what a basis vector...

Inelastic scattering of Xray photons from electrons give them a wavelength shift, the Compton effect. The shift is inverse proportional with the mass of the electron. Now, if visible light scatters inelastic from electrons in graphene what will be the wavelength shift? The electrons in graphene...

Is there any simple justification about graphene having no band gap? How bout its linear E-K? Why bilayer graphene has a quadratic E-K and electric field can open a band gap there? I do not completely understand the broken symmetry argument? Also Why MoS2 which has similar structure, do not...

Hi all. Is there any place where I can check how to derive the DOS of bilayer graphene subject to an external field. I have got the Hamiltonian right and solved the eenrgies but then I am not sure how to obtain the DOS right.. Thanks

Are there any "graphene" Planck-scale quantum gravity? I'm wondering if there is any QG or emergent structure that is "graphene" due to suggestions from this paper, specifically, does LQG, SF, CDT,M-theory, etc., suggest space consists of discrete points arranged in a non-cubic lattice...

I'm taking a graduate course on computational physics which has a project. I'm doing research on electronic properties of graphene, like quantum hall effect measurements. So, I want to do the project related to my research. The project shouldn't be too difficult, as I haven't done simulations...

Hi, In the book of Hanson, the dispersion relationship for a graphene near K points are approximated by E=hbar.vF.k where hbar-> reduced Planck's constant vF->Fermi velocity k-> wave number and then it is said that, since this is similar to the energy of a photon E=hbar.c.k where...

Hello all, I have read a few papers lately that have used DFT based techniques to investigate metallic adatom adsorption on top of graphene (see for instance PRB 77, 235430 2008). I was under the impression that electrons in graphene are described by the Dirac equation and not the...

Hey everyone, So I've been doing research in graphene for a semester and my colleague and I have had no luck making graphene samples. We are using the "scotch-tape" method on Kish graphite. We use a small piece of one flake to put on weak tape (we find that the Magic Tape is too strong...

Hi all, according to textbook definition the effective mass of a particle in a periodic potential is \frac{\hbar^2}{m*} = \frac{d^2}{d k^2} E(k) where E(k) is the energy dispersion. Is this definition applicable at a generic point of a band, or only at the center and edge of the Brillouin...

Hello all, I am beginning a new research project involving graphene. Although I have be actively doing a literature search on graphene, I was wondering if somebody would be will to suggest a good textbook that covers the basic of graphene Thanks in advance -Ed

Hello. I'm trying to find the individual contributions of carbon atoms to the charge carriers in graphene. In other words, I'm trying to answer "How many charge carriers does one carbon atom supply?" Here is what I've done so far: Taking the max. carrier density as 10^13 1/cm^2 and the...

Interesting article I read on how the highly-conductive graphene also begins to exhibit some semiconductive properties at very narrow dimensions: http://www.technologyreview.com/Nanotech/20119/ http://physicsworld.com/cws/article/news/32539 Gee, I wonder if this could keep Moore's Law going?