What is Conduction band: Definition and 44 Discussions
In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level and thus determine the electrical conductivity of the solid. In non-metals, the valence band is the highest range of [[protons] energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. On a graph of the electronic band structure of a material, the valence band is located below the Fermi level, while the conduction band is located above it.
The distinction between the valence and conduction bands is meaningless in metals, because conduction occurs in one or more partially filled bands that take on the properties of both the valence and conduction bands.
Hi
Carriers injected in the conduction band of a bulk semiconductor, either by optical or by electrical injection, are relaxing to the lowest free states near the band edge by transmitting their excess energy and momentum to phonons before they recombine with holes in the valence band. This is...
Hello,
I've seen in a few books on solid state physics that one can deduce an expression for average K.E.:
$$<\:K.E.>\:=E_c+3/2\:k_B\:T$$
from the following:
$$<\:K.E.>\:=\:\frac{\int \:\left(E-E_c\right)g\left(E\right)f\left(E\right)dE}{\int \:g\left(E\right)f\left(E\right)dE}$$
I can't...
Homework Statement:: Ionised atom, free electron, conduction band, donor energy level and acceptor energy level
Relevant Equations:: None
I have some confusion about the concept of some electronic bands and energy levels.
Beyond valance band, in a solid crystal lattice,
For an atom, can...
I am a new to this and I try to understand the basics.
So initially once the atoms of silicon come together to form a solid, due to Pauli law no electrons can exist in the same energy state,thus many energy states are formed which together make the bands.
My problem starts at this stage where I...
I'm having trouble to understand why it's said that electrons in the conductor band are free while electrons in the valence band are not.
I know by the Schrodinger equations that the trajectory of an electron inside a specific band and with a specific energy level is a probability. From what I...
At T = 0K, the valance band of a semiconductor is completely filled, and no current can flow, acting as an insulator. Is there every a situation where the opposite can occur, such that the conduction band is filled (and the valance band is completely empty) forcing the semiconductor to be an...
Hi,
Could you please help me with the queries below?
Question 1:
Please have a look on the attachment, conduction_band2, or check the following link for better resolution http://imagizer.imageshack.us/a/img921/4356/vODcjh.jpg
It says, "Figure 1–7 shows energy diagrams for insulators...
Homework Statement
Homework EquationsThe Attempt at a Solution
The probability of getting a state with energy ## E_v## is ## \frac { N_v } { N_v +N_c } = \frac1{ e^{-(E_v – E_f)/k_BT} +1} ## ………….(1)
Since, ## E_v < E_f, e^{-(E_v – E_f)/k_BT}>>1 ## as ## E_f – E_v>> k_BT ##……….(2)
So...
Homework Statement
How many free electrons are there in the CB? Diamond has a bandgap of ##5.5##eV.Assume the material is at room temperature and that there are ##2 \times 10^{22}## cm##^{-3}## electrons in the material. What does this mean for their use in semiconductor devices?
Homework...
I am studying introduction to solid state physics and it's stated that when germanium is n doped energy states with energy -0.1 ev are introduced, then it's stated that this means that the donor level is 0.1 ev below the Conduction level
Does that mean that the Ec is considered 0??
Hello!
In order to obtain the number of actual electrons in the conduction band or in a range of energies, two functions are needed:
1) the density of states for electrons in conduction band, that is the function g_c(E);
2) the Fermi probability distribution f(E) for the material at its...
Consider the figure from section "Electrical conductivity":https://en.wikipedia.org/wiki/Valence_and_conduction_bands
I understand that below the Fermi level, we have bands of allowed energy separated by band gaps. Then, we have the Fermi level. Then we have the conduction band.
My question...
I know we can shift the fermi level by doping the material with other elements. In case of semiconductors doping with the pentavalent or trivalent will change the fermi level. But my question is ''can we shift the fermi level, without altering the position of valence band and conduction band?"...
Why can't electrons move inside the valence band? Is that the Pauli exclusion principle - and is it true that the electrons can't move even when the valence band is only partially filled?
Why are insulators supposed to possesses a "conduction band", even if usually empty?
If you do take the energy to cross the "band gap" and displace an electron, just why should it become delocalized/conductive? Couldn´t it just lose energy rapidly by exciting phonons until it gets trapped...
Hello,
I am writing a technical essay on solar cells and I am having trouble finding out exactly what the valance and conduction band actually are. It's a bit elusive, the textbooks I am using simply state the two bands without explaining what they are.
If anybody could provide any...
As my title states, I want to understand why electrons in the conduction band can move around so easily in the material. Is it due to the presence of many closely spaced (blurred out) energy levels which make it easy for the electrons to move around? Or are the electrons undergoing some kind...
Homework Statement
Describe the ”conduction band” in Na metal. Why it is half-filled and
non-magnetic?
The Attempt at a Solution
Na has electron configuration: [Ne]3s^1
the 3s band is highest in energy and is the conduction band for Na. since Na has 1 electron in the 3s band, and...
Electrons in the conduction band of metal will be attracted by the nucleus of atom?
I wonder why there can be electron in the conduction band of metal at 0K .At 0K , all electron should lose its energy as(3/2)kT=0.
Thank you
Hi,
Does anyone have an intuitive idea of why it is always the valence bands split under spin/orbit coupling, but not conduction band? (or a much smaller splitting than valence band)
I know through tight-binding calculations, if I plug in numbers correctly, conduction bands always have...
Can a hole go to conduction band?
In p-type, the hole is above the fermi level, lower than conduction band, higher than valence band, how can this be happened? And will this happen when the p-type is at 0K
Homework Statement
Find the density of carriers N in the conduction band of intrinsic silicon at room temperature
Homework Equations
lower integrand Ec, upper integrand= Ec+1*qe,
Eg=1.12eV,
Ev=0
Ec=Ev+Eg
Ef=Ev+Eg/2
m*n=1.08*(9.11*10^31),
T=300K...
Homework Statement
Calculate the number n_0 of electrons per volume unit in the conduction band for the lithium, copper and aluminium. Compare this result with the number of electrons of valence per volume unit of these metals.
Homework Equations
None given, no ressource either...
I was reading about electronic band structure in wiki and I didn't understand why the conduction bands are necessary for flowing current in a material. If all the atoms in a solid shares valence band and all its eletrons, then these electrons may travel through the solid. I didn't get why the...
Hello Forum,
I am looking at the energy levels between the n and p regions of a diode. The p-side has a conduction band that starts at a higher energy (same for the valence band).
The n-side has the valence and condution bands that are at lower energy.
The Fermi energy line is the same...
hello,
i have a question related to metallic bonding.
As far as i know, valence band is defined as the highest filled level in the band and conductionband as the 1st unfilled level. So, if I have 100 Li, we will have 100 orbitals which form a band. Since we have 100electrones, 50 pairs, so we...
Hi and thanks for reading,
I don't really understand the valleys in the conduction band, in the E vs. k diagram, there is the L-valley, r-valley and X-valley. Each has a different momentum... and are at different energy levels.
I understand that at any temperature above absolute zero, a...
Hi,
I understand for metals the conduction band is usually partially filled.
However, at absolute zero, is the conduction band empty (for metals)?
I'm asking this because as far as I know, the definition of valence band is "the highest occupied band at absolute zero"
However, I have...
We know in silicon a valence electron can be excited to conduction band if it absorbs one photon(one photon absorption) or two photon(two photon absorption),my question is that it must need a certain amount of time for the electron to 'travel' from the valence band to the conduction band(I...
I need to calculate the density of states for a dispersion relation which is like the free electron dispersion, but with one effective mass in the kx, ky directions, and a different effective mass in kz. So I need to integrate the inverse gradient of E(k) over a surface of constant energy, ie...
Warning: I'm not a practicing chemist. Answers in as-simple-as-possible language (but not oversimplified!) would be greatly appreciated!
I'd like to know if the chemical properties of a solid can be affected by conduction band electrons. I assume that, in the majority of cases (and perhaps...
Hi, I have a very basic question on formation of valance and conduction band. It is said that conduction band is above the valance band.
So In a hypothetical lithium molecule formation(for example purpose) : If 100 Lithium atoms combine together, then 1S shell is split into 100 1S shells (one...
Homework Statement
1) I try to understand the lorentzian lineshape and relate to the gaussian graph but i don't know what is the difference.
2) Uncertainty principle- if it's related to the lorentzian lineshape it will give the information about the lifetime in the well and the width of...
I'm not from the chemistry major but I need to learn solid state chemistry out of the need of my research. I viewed solid state chemistry lectures online delivered by professor Donald Sadoway from MIT. Particularly on the topic of conductors, insulators, semi-conductors, I have some confusions...
Homework Statement
There has been created a heterojunction of two different semiconductors, Si and GaP. I am to determine the valence- and conduction band offset with Tershoff's model.
Homework Equations
The problem is that I can't find the relevant model. Therefore, I cannot find the...
I am looking to calculate the energy gap of for starters periodic elements and were wondering how we could get the list and calculation. Is there a table somewhere based on certain temperatures and constants of energy gap level? We would like to get a list of the energy gap energy for valance...
Hi all,
From Pauli's principles, electrons cannot move into an already filled state. If i assume that somehow I fill in all the energy states in the conduction band (Population inversion :confused: )and then apply an electric field what happens??
Thanks...
I'm having difficulty figuring out how to work this problem:
Assume a material has a given E-K diagram:
E(K)conduction = Ec + E1 * sin^2 (Ka)
E(K)valence = Ev - E2 * sin^2 (Ka)
a=0.5nm
E1 = 5eV
E2 = 4eV
I have to:
* sketch the E-K diagram for the first brillouin zone (-pi/a < k <...