# Semiconductor Physics

1. Mar 30, 2013

### hogrampage

1. The problem statement, all variables and given/known data
A certain doped semiconductor at room temperature has the following properties: no = 9 x 1014 / cm3, po = 4 x 1014 / cm3, μe = 800 cm2 / V-s, μh = 400 cm2 / V-s, and (Dh$\tau$h)1/2 = 10-4 cm.

If an electric field is applied, what fraction of the resulting drift current flow will be due to electrons?

2. Relevant equations
Not sure.

3. The attempt at a solution
I have no idea what to do, but the answer is 0.82 (according to the book).

2. Mar 30, 2013

### AugustCrawl

Could you perhaps state what you think all the letters mean?

I would guess that:
No is charge carrier density of n type
p is charge carrier density of p type
no idea what μ e and h are ... or what Dh and Tau h are,

In my experience (if this came from a lecturer) he will have given you a formula. Perhaps even with all these terms present.. and the answer may just fall out....

I found this related PDF
http://users.ece.gatech.edu/~alan/ECE3080/Lectures/ECE3080-L-7-Drift - Diffusion Chap 3 Pierret.pdf

It contains equations for calculating hole and drift currents (if you have the right parameters available).

Maybe if you worked out the hole current , worked out the drift current ... and divided one by the other to get the ratio?

Sorry its not a complete answer but it may get you going in the right direction :)