Calculating Fermi Level in Doped Silicon at Room Temperature and 0K

[andarr]

Homework Statement

(a)If a silicon crystal is doped with 10^15 cm−3 phosphorus atoms, find out the electron
concentrations and hole concentrations in the silicon at room temperature. Find
out the Fermi level.
(b)Repeat at temperature = 0K

Homework Equations

n*p=ni^2
n=2(2pi(n*)kT)^(3/2)exp-[(Ec-Ef)/(kT)] where (n*) = electron effective mass

The Attempt at a Solution

I have calculated the hole concentration p = 10^15 per cm^3
and the electron concentration n = 1.96*10^5 electrons per cm^3

but I am not sure where to begin for calculating the fermi level. I don't know what to plug in for Ec the conduction band edge energy. For part (b) I am also unable to find ni, the intrinsic carrier concentration of silicon at T = 0K. Any suggestions or insight would be appreciated, thanks in advance.

 

[hagopbul]

Ef=[(Ec+Ev)/2]+((KT/2))ln(Nc/Nv):if n=p=ni

and i think that you can use Eqs:
Ef==KT*ln{[(1/4)*[e^(Ed/KT)]*([(1+(8Nd/Nc)e^(deltaEd/KT))^(1/2)]-1)}