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

Click For Summary
In the discussion, a user presents a problem involving an n-type doped semiconductor with a bandgap of 0.1 eV and specific densities of states. They initially calculate the electron and hole concentrations but find an unexpected result where hole concentration exceeds electron concentration. Other participants clarify that the user likely mixed up the doping concentrations, suggesting that under the given conditions, the electron concentration should indeed be greater than the hole concentration. The conversation emphasizes the importance of correctly applying the equations related to semiconductor doping. Ultimately, the user acknowledges the error in their calculations.
heehar
Messages
3
Reaction score
0

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?
 
Physics news on Phys.org
You did the math wrong. With those conditions, I get n>p, with n~2*p. Did you mix up Na and Nd?
 
you are right haha thanks
 

Similar threads

Semiconductor Physics : Charge carrier concentration change on doping
  • · Replies 2 ·
Replies
2
Views
3K
Concentration of minority carriers in a pn junction
  • · Replies 2 ·
Replies
2
Views
11K
What exactly is a concentration of acceptor in p-type semiconductor
  • · Replies 3 ·
Replies
3
Views
2K
Why Does the Depletion Layer Affect Acceptor Atom Concentration in PN Junctions?
  • · Replies 3 ·
Replies
3
Views
2K
Silicon NPN Transistor: Calculating Fermi-Level & Equilibrium Concentrations
  • · Replies 1 ·
Replies
1
Views
2K
Diffusion current and carrier concentration equilibrium (unbiased)
  • · Replies 1 ·
Replies
1
Views
2K
Calc Electron/Hole Concentrations & Ef-Efi for Si Doping in GaAs
  • · Replies 7 ·
Replies
7
Views
2K
Semiconductor Doping: Impurity Effects on Energy States
  • · Replies 9 ·
Replies
9
Views
2K
Semiconductor doping - doping concentration is 0?
  • · Replies 5 ·
Replies
5
Views
2K
Electron and hole concentration
  • · Replies 1 ·
Replies
1
Views
2K