1. ### I Fermi Energy Calculations About Non Parabolic Dispersions

Greetings! It is easy to understand that for a free electron, we can easily define the energy state density, and by doing the integration of the State density* Fermi-Dirac distribution we will be able to figure out the chemical potential at zero kelvin, which is the Fermi-Energy. Hence, we can...
2. ### I Valence band and Fermi level difference?

I was wondering what the difference was between the valence band and fermi level? How do we distinguish between the two? Thanks in advance.
3. ### [PoM] Electrons Fermi level in a crystal

Homework Statement The conduction band of a hypothetical crystal of one-dimensional Cesium reticular with step a=300 pm (1 atom per cell) is characterized by the ε dispersion law ##\epsilon (k) = V_0 + \frac{\hbar^2}{m_e}(\frac{1}{2}k^2 - \frac{a}{3\pi}|k|^3## where ##V_0 = -4 eV##, is set so...
4. ### I Negative Magnetoresistance?

A free electron gas would have zero magnetoresistance; it takes two carrier types to get ordinary magnetoresistance, which is always positive in sign. Beal-Monod and Weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spin-flip scattering of...
5. ### I Double heterostructure junction in forward and zero bias

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...
6. ### I Effect of SAM physisorbed on graphene - some questions

Hello everyone! :) I'm sorry that I'm posting something that might be obvious, but I'm still struggling to capture all the concepts behind the fundamental physics of this model. Let's say, I have a 2D sheet of graphene, on which, theres a physisorbed layer of molecular dipoles (vdW bonding, no...
7. ### Relation between electronic band structure and Fermi energy

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) ...
8. ### Is it possible to shift the fermi level?

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?"...
9. ### Density of States of a metal at Fermi level

Why can not the density of states of a metal at Fermi level be zero? Thanks!
10. ### Silicon npn transistor

Homework Statement we look at a silicum n++ p+ n transistor. given: NE= 1,0×1018 cm–3; NB= 2,0×1016 cm–3; NC = 2,0×1015 cm–3; here E stands for the emitter, B for the basis and C for the collector Homework Equations a. calculate the distance in eV from the fermi-level to EFi for the...
11. ### Fermi Surface squashed by potentials

Taken from my textbook: My understanding is that: One valence electron, 2 spin states -> Half-filled Brillouin zone Seeking inspiration from "Nearly Free Electron Model": gaps open up at zone boundaries States nearer to zone boundaries get pushed down in energy further Since a fermi...
12. ### [Semiconductor] Aluminum doped Silicon, valance band&holes

From some literature, I read the following band structure of the Al doped Si. The explanation offered: "have vacant acceptor levels at energy Ea above the valence band. Electrons from the top of the valence band can be easily excited into these levels." I thought the above explanation is...
13. ### Free electron concentration range between semiconductors and metals

A structure with free electron density around 10^26 m^-3 is considered as a highly doped semiconductor or a metal? Or in other words, what is the lowest possible free electron concentration for a metal and what is the highest possible free electron concentration for a doped semiconductor?