What is Band: Definition and 531 Discussions

Dear forum people I consider four atomic orbitals of the silicon atom: s, px , py and pz , thus Hi,j is a 4*4 matrix. Hi,i is the expression of the diagonal matrix and Hi,j is the expression off-diagonal matrix where the expression for Hi,i and Hi,j is attached. But I can not calculate the...

So I know glass is transparent because the electrons have energy bands(or the energy to get it up to the next energy state) that are beyond the energy of visible light. But what I what to know is why do the electrons have energy bands because every single electron is the same and there all...

Landau level is the energy levels of free electron gas in a magnetic field. However, this term is also frequently used in solid state physics. I have the following questions: 1. what does this term exactly mean in band theory? After all, electrons are not free here. 2. why is de Haas-van Alphen...

Dear forum people, I know that electronic properties silicene is the same graphene but i can not figure out how can I plot band strcture silicene. I want to plot that in the following path: K→Γ→M→K

Homework Statement Dear forum people, I know that electronic properties silicene is the same graphene but i can not figure out how can I plot band structure silicene. I want to plot that in the following path: K→Γ→M→K

Homework Statement Emma and Don are playing in a band. While emma is marching toward Don, Don tunes his instrument to match the note that emma is playing. When emma stops, don immediately notices a beat frequency of 5 Hz. If the speed of the sound is 330m/s what is the relationship between...

As far as I am concerned, dielectric function can be computed by band structure. However, band structure is a global property of solids, while dielectric function is a local property. How a local property can be computed from a global property. Put it another way, if I want to calculate...

Hi all, I am currently writing a report about superconductors, and am currently reading about how the band gap shows that single electrons are not the charge carriers responsible for superconductivity. However, I was confused when I read that electrons are fermions and as such there are no band...

What's the electric field strength needed to get one of lithium's core electrons into the conduction band? How do you figure this out?

Hello all, I am anew user for Ansoft Maxwell, I am doing simulation for tubular machine in 3D, I have problem with band assignment, when I run the analysis there is a massage error after the mesh, which said [error] Error in mesh mapping on band, please check the potential problem in band...

Can you show me as explicitly as possible through equations?

Hello As you know AlGaAs and GaAs have different band gap).I want to know what will happen when we connect both of them to each other? In this figure I don't know how can we draw the jump in their junction. Could you tell me what does fermi level do? Thanks

Dear all, I'm a common user of Maxwell v15, though this is the first time I've tried to work with Linear Motion and Force calculation in it. I've got two solids translating in my model, and they get in a electromagnetic field área. I want to calculate the braking force in each object, so I've...

I just learned how to get a tight-binding dispersion for graphene. But i can not figure out how can I plot that. I want to plot that in the following path: Γ→K→M→Γ I would be appreciated if could some one give me a hand on my problem. thanks for alot.

Short version: how do I figure out how much error I get when measuring light intensity vs wavelength for a given monochromator band pass width? Long version: I have a project where we will be passing white light through liquids, then looking at the spectrum intensity of the light with a...

Look at the diagram below, after all that doping, 2 blocks of Si have the same band structure? My understanding of band structure and fermi level is that: Given a block of solid (Please note, not a TYPE of solid, but this PARTICULAR block of solid) it will have its own unique band structure...

i would like to know all the details about the band structure in a semiconductor and in particular what we call : yours sincerly guedman

I didn't put this in the Education forum because I feel the level is probably too high. I have a physics degree and an education degree, but due to my inability to tolerate students who simply don't care about learning, I became an electrician instead. My colleagues and I were having a...

It's known that the number of states in a band is equal to the number of unit cells in crystal. Here is my problem (confusion with trivial concepts) Bloch function is a electronic state, or orbital. The number of orbitals in a band inside the first zone is equal to the number os units cells...

<< Mentor Note -- post separated out of a different thread to deal with a separate question >> Hi, I am looking transmit as well as receive power within close proximity. Currently I am looking at 27.255 MHz AM in the citizens band. It is listed on Wikipedia and in statues I found to be for...

For a wavefunction at the Brillouin boundary we have: \langle k|H|k\rangle = \epsilon_0 (\vec k) \langle k'|H|k'\rangle = \epsilon_0 (\vec k+\vec G) \langle k'|H|k\rangle = V_G = \frac{1}{L^3} \int e^{i(\vec k - \vec k') \cdot \vec r} V(r) d\vec r \langle k|H|k'\rangle = V_G^* Using...

When electrons leave the valence band and jump over the gap to the conduction band, what is the density of the remaining holes? If 2.5 electrons/cm^3 leave the VB to the CB, will the density of remaining holes be 2.5 electrons/cm^3? To me it is logical, but I am wondering if mass of electron...

My question is as follows: if you place an insulator into an applied field, the only thing that will happen is that the potential energy of each band will shift, according to the potential that it is in. Why is this exact same thing not what takes place in conductors? Why do the electrons at the...

So every theoretical resource I've been able to find seems to map bands to lines for a 1D crystal, surfaces for a 2D crystal, and hypersurfaces for a 3D crystal. But then there are images like the ARPES data below (fig. 1a, 1b, 2) where the density of states is a lot higher within the valence...

I'm studying a two dimensional lattice with delta functions at the lattice points. When I diagonalized the hamiltonian I noticed that if I kept the dimension of my matrix less than 5 I would get band gaps at all the BZ boundaries. However, if I increased my matrix to a dimension 5 or higher...

Hi everyone:) Is there anyone who has worked on the phenomena near the band edge of photonic crystals? for example spontaneous emission near the band edge? there are lots of articles specially from Sajeev John " spontaneous emission near the edge of a photonic band gap" Phys.Rev.A vol50 num 2...

I am struggling in understanding what the band structure (E vs. k) diagram tells me. Let's say I have the following material: http://www2.warwick.ac.uk/fac/sci/physics/current/postgraduate/regs/mpags/ex5/phonons/indirect_absorption/indirect_absorption.bmp...

Homework Statement For a stretched rubber band, it is observed experimentally that the tension f is proportional to the temperature T if the length L is held constant. Show that: a) The internal energy U is a function of temperature only b) Adiabatic stretching of the band results in an...

I'm trying to reconcile how a built-in potential can form in a semiconductor heterojunction in which there is a significant band cliff to majority carrier diffusion from both sides of the junction i.e. there is a cliff which should block hole diffusion from the p-type as well as a cliff which...

Is there any possibility in silvaco TCAD to introduce Band gap in material. i want to use different energy band gap for different transport direction of a material. i.e.transverse direction one energy gap value and longitudinal directon different energy x-axis one energy value and y direction...

Hi,there are many literatures concered with band decomposed charge density(As an example,see FIG.3 in PHYSICAL REVIEW B 78, 235430 2008). For condution band,there should not be charges or electrons when the system is in the ground state,but,those literares still show a band decomposed charge...

Hi Guys, i need your help, where can i download free articles about the band gap of semiconductor materials (like copper (II) oxide). don't mention sciencedirect and arxiv, because i already explore that, and they provide limited research articles. thank you.

Homework Statement Consider an n-type Si (Eg =1.1eV, ED=EC, εr=11.8) with a bulk doping density ND=1×1017cm-3, a density of acceptor type surface state 1×1014 cm-2 and these states are at the middle of the band gap. Evaluate the amount of: a) band bending b)depletion layer thickness c) density...

The ISM band is a set of frequency bands from about 6 kHz to 246 GHz; see http://en.wikipedia.org/wiki/ISM_band#ISM_bands. Is there a design that will block all of these bands? A guess is in the attached file: each box is solid metal or wire mesh, and the boxes nest in a Matryoshka-doll fashion.

Hi, I'm a second year Design Engineering student. This year we're having some basic physics class. We're doing projects on potential energy at this moment. I'm having a problem with the following; The assignment: The teacher assigned us that only 6 Joules of potential energy may be used to...

I'm a little confused by the description I commonly hear about the electron "counting rule" in band theory. The general statement I find is that a solid with an "odd number of electrons per unit cell is a metal" (because this would imply a partially filled band), while an "even number of...

Homework Statement Hi everyone, I am trying to construct qualitative band diagrams and I think I have confused myself. I am not sure on how to figure out what the electron configurations are of the orbitals when k=0. I get that at k=π/2 it is the opposite state but I can't seem to figure out...

I'm trained in Condensed Matter Physics, and I'm trying to learn EE. The concept of band bending always baffled me a bit. Here's why: The band edge bloch states are delocalized over the whole of the crystal, and have fixed given eigenvalues. How can this eigenvalue change over the length of the...

Hi! I am having difficulty grasping what band theory actually is, especially what the bands are and the energy gap between them. Are they probabilities? Shared electrons between atoms such as in metallic bonding? What is the difference between the conductor band and the valence band? I think I...

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...

Hey guys, So this is entirely theoretical and I am just curious if its possible and how it could be done. But how can you go about changing the bandwidth of a particular signal? So a lot of times we have a signal at a given frequency, and there might be a little bit of aliasing into other...

I have done the computations of band structure of cobalt adsorbed graphene. In 3x3 supercell of cobalt adsorbed (one cobalt atom) graphne, there is opening of band that is gap between conduction and valence band but there is no gap in 4x4 supercell of cobalt adsorbed graphene. I've done this in...

Does this mean if I had a rubber band and weighed it, then stretched and weighed it while being stretched out, that it would weigh more at that time? Since at that time it has stored energy, which equates to mass?

Homework Statement "You have a 1 km long rubber band with one end attached to the wall, and the other in your hand. The bug begins to crawl towards you on the rubber band, starting from the wall, at a rate of 1 cm/sec. As he crawls the first centimeter you extend the rubber band 1 km; when he...

i search all over the web but i cannot find the definition. Although I find all the literature saying that metal have valence band and conduction band overlapped, (and I cannot find a metal example with valence band and conduction band not being overlapped), I wonder if there is a...

According to solid state texts in Brillouin zone borders where diffraction condition satisfies we have a band gap. However I usually see Band gaps which are located in the center of Brillouin zone. Please correct me if I am wrong.

My understanding of the atomic structure is that electrons can gain energy in quantas, so that's why we have orbitals with sharply defined energy around the nucleus. One would logically think that every atom of the same element has the exact same orbitals with the exact same energy of orbital...

I am reading about the ionization energy in semiconductors and came across this thing that for Silicon, the ionization energy is lower than its band gap energy. I don't understand how can this be?

how the dispersion relation(i.e. E-k relation) affects carrier mobility in metals or semi-metals?

Could anyone please explain the concept of Band offset?