# Fermi Dirac probability

1. Sep 9, 2016

### falcon555

Hi dear friends
Please reffer to my work , I did part ( a ) only
I don't know how to do it.

2. Sep 9, 2016

### rude man

(a) is correct.
(b): If p is the fraction of electrons in the conduction band (at energy EG/2) & coming from the valence band, what would be the fraction of holes left behind in the valence band, seeing as those electrons came from the top of the valence band?
Hint: no electrons going to the conduction band ⇒no missing holes!

3. Sep 9, 2016

### falcon555

Thanks rude man.....
I'm not getting what you mean. ....
Can you explain it in a different way or show on a diagram. ...

4. Sep 10, 2016

### rude man

I may work on this some more but I think you should post this in the advanced physics section where I think it belongs. I covered this material many years ago in a graduate course (taught by a future Nobelist!).

5. Sep 10, 2016

### falcon555

Then the equation may change to the below

I guess. .
If this is correct then we have to write an equation for W h in term of Wg and Wf to eliminate Wf.
What will be that equation?

6. Sep 10, 2016

### falcon555

How to shift this post to the advanced physic section?

7. Sep 10, 2016

### rude man

OK, after a bit more perusal on my part:

My textbook gives the probability distribution for holes as not W(p) as it is for electrons, but as 1 - W(p). Without a believable rationale, but I'm sure it's correct, because later on they use that expression for deriving the totality of free carriers for electrons and for holes and get roughly the same number for each, which has to be correct. That was supposed to be my hint in post 2 but as I say it wasn't based on good argument.

So, bottom line, if you use 1 - W(p) for the holes, and use Wv in lieu of Wc, and proceedig exactly as you did in part (a), you will get your answer. Do that and let us know what you come up with.

I am going to ask a moderator to move your post to the advanced physics section for you.

Last edited: Sep 10, 2016