Talk:Band diagram

Notes for improvement

Hello,

I addition to the figures described below the key figure needed is one that relates, say, the simple band structure of a 3D-semiconductor to the band diagram. I am not sure if depicting the semiconductor, semi-metal and metal would be too much, but why not include more information rather than less? Also, the origin of this concept needs to be added to the band structure page so that one can then be directed here for more information and a more detailed explanation. Jatosado (talk) 07:29, 17 June 2014 (UTC)

I'm planning to improve this article. Here are some notes on improvement.

The article needs at least three figures giving band diagram examples: in order of increasing complexity,

1. Full equilibrium band diagram: Fermi level constant everywhere. Just need to plot bent band edges and Fermi level.
2. Biased insulator band diagram (nonequilibrium): Separated conductors have different Fermi levels. Insulator (vacuum or material) has no Fermi level but does have a band edge.
3. Active mode band diagram: Band diagram for device such as a solar cell. Shows different quasi-Fermi levels for different bands.

At least one figure should go beyond basic Si-Si junction to point out that band edges are not continuous across a heterojunction.

It is probably worth pointing out that it doesn't make sense to plot "the vacuum energy level" inside materials. Also, it can't be so oversimplified that people forget surface states and Fermi level pinning. --Nanite (talk) 16:41, 26 May 2013 (UTC)

Sounds great, good luck!

I wrote an equilibrium-band-diagram calculator - link - let me know if it would help for me to upload one of those images to wikimedia, or to generate the equilibrium-band-diagram of any other structure you like and upload that.

There is a framework of analysis that encompasses both Anderson's rule (at semiconductor-semiconductor interfaces) and the Schottky-Mott rule (at semiconductor-metal interfaces) ... the framework where there is something called the "vacuum level", which is continuous, and which is exactly equal to the voltage V (i.e. electrostatic potential, a.k.a. Galvani potential) multiplied by the electron charge (-e), plus some universal shift, and which is related to the energy of an electron at the conduction band or valence band of any particular material at any particular point in a straightforward way, as described by electron affinity, work function etc. I'm sure you're familiar with this.

Well, this framework of analysis is not exactly correct, and in some cases (like predicting Schottky barrier heights) it is not even approximately correct. Your comment suggests that you understand this. I guess I just want to say, this framework of analysis is nevertheless very widely used, and if you have time I hope you write a section that thoroughly explains the framework ... even if in the end you say that the framework is not really correct (which you should indeed say). :-D --Steve (talk) 12:45, 27 May 2013 (UTC)

Right, I think I know what you mean. I guess I've been using Anderson's rule all along but I didn't know that it was called that. Your suggestion is good. Although most of the examples I have in mind will just show the result (only showing vacuum edge where there is a vacuum), I'm definitely planning to have such a section somewhere on exactly that topic. The question is, where exactly to put it (perhaps it's also worth mentioning as a "limit of applicability" for Anderson's rule, Heterojunction, Metal-semiconductor junction, Schottky barrier, etc....)

Nice program by the way. I am a big fan of python and matplotlib. :) By the way, I noticed that GSL has a fermi-dirac integral which might be useful to get more accuracy on your highly-doped regime. --Nanite (talk) 21:22, 27 May 2013 (UTC)