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3
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1answer
243 views

Hartree-Fock correction to $e$-$e$ interaction

The corrections to the energy per electron in a jellium model (uniform distribution of positive ion charge approximation to the regulated long range order ionic array) is given by (in units of Ry) ...
2
votes
1answer
71 views

how do electrons in 2 separate atoms change its energy level when atoms come close together to form molecule?

The question is just as the title. It's said that electron must receive a specific amount of energy in order to go or drop to another energy level. So how can electrons of separate atoms which have ...
9
votes
0answers
1k views

Where does the Berry phase of $\pi$ come from in a topological insulator?

The Berry connection and the Berry phase should be related. Now for a topological insulator (TI) (or to be more precise, for a quantum spin hall state, but I think the Chern parities are calculated in ...
3
votes
0answers
56 views

What is the effective electron mass in a plasma?

Is there a way to calculate the effective electron mass in plasmas? Effective electron mass is usually defined as varying from the vacuum electron mass in solid state physics. However, momentum ...
3
votes
0answers
96 views

What is the physics behind “Bulk-edge correspondence”?

There is a frequently mentioned concept in the field of topological insulator called "bulk-edge correspondence" or "bulk-boundary correspondence", which basically gives the relationship between the ...
2
votes
0answers
33 views

Estimating Energy Bands For Dirac Comb Potential

With $$V = \sum_n aV_0(x-na) $$ I can solve exactly up to $$\cos(k a) = \cos(\kappa a) + \frac{2ma^2V_0}{\hbar^2}\frac{\sin(\kappa a)}{\kappa a} = f(\kappa a)$$ Where $E = \frac{\hbar^2 ...
2
votes
0answers
57 views

Materials for use in a solar cell

In a solar cell, photons of the incident sunlight supply energy for excitation of electrons - a process which generates electron-hole pairs which can move under the influence of the electric field of ...
2
votes
0answers
353 views

Derivation of existence of energy band gap in semiconductor (solid State)

I am looking for both a mathematical and a physical reason for energy band gap in metals. For Physical reason, I was told that at each reciprocal lattice, you could have Bragg scattering, that would ...
2
votes
0answers
144 views

Why does silicon have an indirect gap?

Is there an intuitive explanation as to why silicon has an indirect gap? I have heard that this can explained using pseudopotentials.
1
vote
0answers
17 views

Optically access a single valley in indirect semicondutors

An indirect semicondutor has an energetic minimum of its band structure at a point different from the $\Gamma$ point. But, there are multiple of them. Silicon for example has its band minimum at the ...
1
vote
0answers
34 views

Band-gap for solids with isoelectronic atoms

Isoelecronic atoms have same number of electrons but different nuclear charge. It is said that many of the chemical properties of these elements are equal or at least similar. Can I form solids with ...
1
vote
0answers
45 views

DOS behavior of Van Hove singularity in a line

When there are some points in momentum space give $|\nabla_k \varepsilon_k|=0$, they are called Van Hove points and give singularity in the desity of states (DOS). But what if $|\nabla_k ...
1
vote
0answers
170 views

DOS of Van Hove singularity in 2D square lattice tight binding model

For the simplest example, 2D square lattice tight binding model gives the energy band as $$\varepsilon_k=-2t(\cos k_x+\cos k_y) \, .$$ We know that $\vec{k}=(0,\pi)$ and related momentum points are ...
1
vote
0answers
100 views

kp theory of QW band structures in envelope function approximation

I am currently trying to calculate wave functions and energy dispersions for quantum well heterostructures. The kp method is my choice to do that. I already calculated band structures for bulk ...
1
vote
0answers
49 views

Why graphene's substrate is important

I just have some feelings that somehow it is important what specific subtrate is used to grow graphene monolayer on. Some substrates are better, another ones are not so good. But I cannot completely ...
1
vote
0answers
82 views

Problem with energy bands

I am getting confused by the energy bands. As far as I know, the outermost shell of an atom is called valence shell. The electrons residing in that shell participate in reactions and conduction of ...
1
vote
0answers
273 views

Problems while numerically computing band structure using k.p theory

I want to use k.p theory to numerically compute the band structure of a bulk semiconductor. The band I like to include are the lowest conduction band (cb), the heavy-hole (hh), the light-hole (lh) and ...
1
vote
0answers
272 views

Why the current through a resonant tunnel diode drops when the bound state goes below the conduction band?

The IV curve of a resonant tunneling diode is N-shaped. The rise in current flow happens because the bound state (the energy state in the well) enters the thermal area of the conductor ($\mu_1 + ...
1
vote
0answers
62 views

Symmetry breaking and band gaps?

Can the discontinuity in the E-K dispersion relation of a periodic lattice (at the boundary of a Brillouin zone) be understood as a consequence of breaking continuous translation symmetry into ...
1
vote
0answers
84 views

How come graphene is considered to have two valleys?

The typical graphene band-structure is a double-cone (in opposite directions to each other) with Dirac point in the middle. I assume the bottom cone is like the valence band, while the top cone is ...
1
vote
0answers
32 views

How can we determine the inbuilt barrierpotential and electric feld for a given band diagram?

Suppose I have got two p type silicon materials of different concentrations (the difference in thier concentrations is small but considerable enough that their fermi levels differ by noticeable ...
1
vote
0answers
24 views

Is there a way to quantify how similar a polycrystal should behave to a single crystal?

So in solid state classes we learned about phenomena like band structure and others arising from a periodic potential. Then we get to doing actual experiment and find out that materials being single ...
1
vote
0answers
12 views

Hydrostatically compressed crystal

When a crystal is hydro-statically compressed, the band gap becomes larger, however I am unsure why. Can anyone explain why to me in detail though?
1
vote
0answers
106 views

Nature of electron states in a semiconductor

Usually one is led to think of an electron moving from the valence band to the conduction band as an electron leaving the atom it is bound to in the lattice, and becoming free to move, while leaving ...
1
vote
0answers
212 views

Energy band diagram of a metal-silicon-metal device, bias voltage applied

I have an intrinsic silicon layer sandwiched in between two aluminum contacts. I'm trying to figure out the band diagram of the entire device when a positive bias (much larger than the work function ...
1
vote
0answers
445 views

Some questions about the edge states for time-reversal invariant topological superconductors?

Stimulated by my some recent calculations on edge states(ES) for time-reversal invariant(TRI) topological superconductors(TS) as well as many questions concerning the "edge states" in Physics ...
0
votes
0answers
25 views

Why for each electron – hole recombination, an electron from the negative terminal of the battery is released

Why for each electron – hole recombination, an electron from the negative terminal of the battery enters the N-region and then drifts towards the junction?
0
votes
0answers
39 views

Band gap origin

Many introductory books on solid state physics use images that I find confusing. For instance, one picture I see alot when reading about the band gap, is similar to this one: I understand that the ...
0
votes
0answers
19 views

Choosing a basis state for density functional theory calculations

How do we choose basis set of wave functions for expanding the eigenfunctions of the kohn-sham equations? I mean given a material,what should i look for in order to choose my basis functions?
0
votes
0answers
18 views

Band structure and k vectors

If there is a restriction on the allowed states (k vectors) for a system, ie the no of states is equal to twice the number of unit cells in the crystal.. why do we plot k continuously on the x axis? ...
0
votes
0answers
27 views

element effect on quantum dot band gap

Main Question: Why do Au QDs have quantum confinement effects which change optical behavior from the bulk Au, whie certain other elements (such as Fe) are typically not shown to have the same ...
0
votes
0answers
27 views

determination of electron dispersion curves

I am somewhat new to quantum physics and I am studying electron dispersion band structures of SiC like the one here I want to know what spectroscopic techniques/methods or if they are spectroscopic ...
0
votes
0answers
31 views

What is the “point” of STM?

Scanning tunneling microscopy (STM) measures density of states (DOS) in a sample. But angle-resolved photoemission spectroscopy (ARPES) measures the bandstructure $E(\mathbf{k})$ in a sample, from ...
0
votes
0answers
18 views

What is the meaning of band structure in the case of amorphous materials?

A consistent band structure is expected in crystals, because "everything is uniform". Theoretical calculations of band structure are also based on infinite lattice. In amorphous materials, however, ...
0
votes
0answers
22 views

How to determine the Fermi energy in Schottky barrier FET(SB-FET) channel?

The structure of Schottky Barrier FET(SB-FET) is almost the same with MOSFET. The difference between SBFET and MOSFET is the contacts change from Ohmic contacts to Schottky contacts. I know the way ...
0
votes
0answers
44 views

Analysis of a Fermi surface

The following image shows the Fermi surface of Pb, plotted with XCrySDen. I have some difficulties in uderstanding the characteristics of that Fermi surface, in particular how to distinguish the ...
0
votes
0answers
39 views

what can be the BG and dielectric constant of monolayer MoS2 in semiconducting state (2H) and in metallic state (1T)

Monolayer MoS2 is a semiconductor that can undergo an MIT (Metal to insulator) or semiconducting state to insulating state transition. The semiconducting state is referred as 2H State and the metallic ...
0
votes
0answers
81 views

Band Structure from Fourier Transform Solution of Dirac Comb

I have use Fourier transforms to solve the Schrödinger equation for an attractive Dirac-$\delta$ comb potential of the form $$ V(x) = -\alpha \sum_{j = -\frac{N}{2}}^{\frac{N}{2}} \delta \left( x - ...
0
votes
0answers
20 views

Can I use an IV curve alone to differentiate between metallic, semiconducting and insulating materials?

Assuming the size of the bandgap is expressed as resistance in the IV curve, could I tell between metals, semiconductors an insulators by only doing an IV sweep? For example very high slopes (large ...
0
votes
0answers
26 views

Do the band lines along high symmetry points contain all the information of the first Brillouin zone?

When calculating the electronic structure of solids, one usually plots the band structure along a certain set of paths that connect high symmetry points in the first Brillouin zone(IBZ). I wonder ...
0
votes
0answers
69 views

How to get DOS of Van Hove singularity using quadratic dispersion relation

Take 2D case for example. We can first get the area in momentum space for all $k$ that satisfy $E_0<E(k)<E $, say $S(E)$. And the density of state (DOS) is $\rho(E)=\frac{\partial S(E)}{\partial ...
0
votes
0answers
78 views

Relation between energy band gap and atomic number

Is there any relation between energy band gap in group4 elements and their atomic numbers? It might be just a trivial observation but I noticed How from Carbon to Germanium the band gap went from ...
0
votes
0answers
18 views

Silicon interface trap filling in nonequilibrium conditions

I need to know probability of filling of interface traps with energy levels located in silicon bandgap. In equilibrium conditions I can use Fermi level and Fermi–Dirac statistics to calculate ...
0
votes
0answers
54 views

Klein paradox in graphene

When considering the Klein paradox in graphene Katsnelson, Novoselov and Geim introduce a potential barrier (see http://www.nature.com/nphys/journal/v2/n9/full/nphys384.html). But I cannot understand ...
0
votes
0answers
31 views

Why are reciprocal lattice vector periodic, and time-frequency not?

k-space vectors are related to each other by $k=k'+G$, where $G$ is the reciprocal lattice vector $G=2\pi/a$. This means that the frequency of oscillation in real space of a plane wave $e^{ikx}$ is ...
0
votes
0answers
26 views

Strain effects on conduction band edge in k.p theory

While including strain effects into the k.p theory, I often see that the heavy- and light-hole band edges are modified due to the strain, but not the split-off or conduction band edges (e.g. this ...
0
votes
0answers
53 views

electron-electron interactions in 1-D electron gas

The electron-electron interaction contribution to the hamiltonian in $k$-space representation is given by ...
0
votes
0answers
811 views

How are band gap energy, dielectric constant (permittivity) and resistance related to each other?

The following three properties are related to current flow: Band gap energy Dielectric constant Resistance I would expect them all to have the same trend (i.e. higher band gap energy would cause ...
0
votes
0answers
28 views

Couting the occupied states in band structure

I work with several dft codes and I have produced the band structures of some doped semiconductors with their plots. The problem I have is that I do not know how I can analyze the band structure and ...
-4
votes
0answers
12 views

Help finding peak electron concentration?

Any tips or thoughts on how to do this problem? Thank you!