How can I see, by looking at a band structure if the substance in question can be viewed as a free electron gas (FEG) or not?
What characterizes a FEG in a bandstructure plot?
Thanks in advance!
Hi!
I never really understood band structure diagrams. I think they represent the energy of an electron, with the given circumstances, at a k vector.
Are the electrons only allowed to be on the lines here? Or can they also be in areas enclosed under/between certain lines?
What are some...
So I thought I understood something well, and then I went to explain it to someone and it turns out I'm missing something, and I'd appreciate any insight you might have.
If I think about Bloch's theorem, it states that
ψk(r)=eik⋅ruk(r) where uk has the periodicity of the lattice. If u is...
I am trying to use the k.p method to study quantum well band structure. One example Hamiltonian look like this [J. Appl. Phys., 116, 033709(2014)]
where
##{{\hat k}_ \pm } = {{\hat k}_x} \pm i{{\hat k}_y}##
and the matrix elements are function of ##{{\hat k}_i}##
and if quantum well is...
I am trying to do some calculation based on a k.p model of GaN proposed by S. Chuang [Phys. Rev. B, 54, 2491]. It is a 8 by 8 Kane model with basis functions:
The 8 by 8 Hamiltonian contain first order of k is
where ##{k_ \pm } = {k_x} \pm i{k_y}##
the reciprocal space and high symmetry...
Hello!
The time reversal operator, ##\hat{\Theta}## transforms a Bloch state as follows:
##\hat{\Theta} \psi_{nk}=\psi^*_{nk}##.
How does one proceed to prove the condition that ##\psi_{nk}## and ##\psi^*_{nk}## must satisfy in order for our system to be time reversal invariant?
Thanks in advance!
Hi everyone, I have been studying the physics of solar cells for a long time. The only thing that I can not completely understand is the physical operation of solar cell based on band diagram.
Can anyone briefly explain the movements of carriers from one electrode to the another based on band...
Homework Statement
I am asked to discuss the band structure of diamond. I saw the band structure of diamond has 4 filled valence bands and then 4 conduction bands. Silicon, the same.
Homework Equations
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The Attempt at a Solution
I'm feeling really silly because I don't understand why it is...
Hi,
I'm looking into how phonon dispersion changes with pressure analytically and need to know how the atomic spacing in copper changes with pressure in order to model the crystal. I can't find any helpful papers online :(
Any help would be appreciated
thanks
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Hello,
Let's suppose we have a two dimensional lattice which is periodic along certain direction, say x-direction, allowing us to define a quasi momentum k_x. The lattice is not periodic along the y-direction (perpendicular to x-direction). Therefore, we are able to obtain the band structure...
I was studying about Crystal defects in crystals and came to know that it has huge effect on band diagram.I don't know about their specific impact on band diagram.So what are major impacts of crystal defects on band diagram.?
Hi!
When dealing with a pn homojunction, it is easy to see the features it has at equilibrium, and also the features it has with forward/reverse bias. Plots show the constant Fermi level at equilibrium and the different Fermi levels for a forward bias; moreover, examples show how much the bands...
Hello!
The (potential) energy of an electron in a solid structure is always negative; also the E_c and E_v levels (conduction band and valence band limits) are negative, in the band diagram of a pn junction.
When the junction is built and thermal equilibrium is reached, the depletion region...
Hello!
Some of the processes caused by a pn junction are not clear for me. Just after the contact between the p and the n region, a migration of charges happens in a semiconductor junction in order to reach an equilibrium condition. A valence band and a conduction band are present in both...
I have some qualitative questions about the relation between band structure, density of states, and Fermi energy (or Fermi level).
1) Say you have a given electronic band structure (energy as a function of k) obtained by any method. How do you relate this to the Fermi energy (or Fermi level) ...
Homework Statement
I am running CASTEP DFT software to simulate pristine graphene, and am unsuccessful in obtaining the trademark zero band gap at the k-point as reported in numerous papers to date.
Any assistance would be greatly appreciated as the subject is very new but I am keen to push...
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...
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...
I have been contemplating for a few days now about how one could think about the electronic structure of Liquid metals. The cases of an isolated atom or that of solid metal crystal are well known and easy to understand. Though, a google search reveals (to me) that nothing much has come out for...