Why Does N-Type Doping Result in Higher Hole than Electron Concentration?

[heehar]

Homework Statement

Suppose an unknown semiconductor material has bandgap energy of .1 eV. Density of states for conduction and valence bands are both = 10^18cm^-3.
If the material is doped with shallow donors (n-type) Nd=10^17cm^-3, what is electron and hole concentrations?

Homework Equations

ni=sqrt(Nc*Nv)*exp(-Eg/2kT)
n+Na=p+Nd
p=ni^2/n

The Attempt at a Solution

so I set Na = 0. and solve the quadratic equation but I end up with a hole concentration greater than an electron concentration...why is that the case? isn't the fact that its doped n-type mean the n concentration is supposed to be greater?

 

[phyzguy]

You did the math wrong. With those conditions, I get n>p, with n~2*p. Did you mix up Na and Nd?

 

[heehar]

you are right haha thanks