# Question on donor concentration in thermal equilibrium

1. Oct 8, 2009

### snoothie

1. The problem statement, all variables and given/known data

In a sample of GaAS at T=200k, we have experimentally determined that n0=5p0 and that Na=0. Calculate n0,p0, and Nd.

2. Relevant equations

3. The attempt at a solution
Have solved that ni for GaAS at 200k is 1.2687cm-3.
And using the mass action law equation, p0=ni2/5p0. I derived p0=0.567cm-3 , n0=5p0= 2.8363cm-3.

Can someone confirm if it is right to say that the donor concentration, Nd is approximately equal to n0 in this case? Since the equilibrium equation state, if Nd >> ni, then n0 is approximately equal to Nd.