1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Semiconductor Physics - Density of States Calculation Problem?

  1. Sep 20, 2012 #1
    1. The problem statement, all variables and given/known data

    Determine the total number of energy states in silicon from the edge of the conduction band to Ec + kT for T = 300K.

    2. Relevant equations

    N = [itex]\int[/itex]g(E)dE

    3. The attempt at a solution

    I'm pretty sure I know how to do this one. The only problem is, when I get to the step where I have to plug in numbers (i.e. the equation becomes N = (2/3)(4[itex]\pi[/itex](2mn*)(3/2)*(kT)(3/2))/h3), I cannot calculate it!

    Reason: Obviously Planck's Constant cubed is an INCREDIBLY small number, and my calculator takes exception, just rounding to 0. There must be a way around it, or a rearrangement that helps, but I don't know what to do. Any advice? Sorry if my equation is formatted a little strangely.
     
  2. jcsd
  3. Sep 20, 2012 #2
    Update: Realized I could use Google to calculate such a sum, and got the answer! Now I have a new problem.

    The second part of that question asks for the same thing, but for the holes. It gives the effective hole mass as 5.10*10^-31. T = 298K this time. When I plug in the values, I get about 1.4*10^19 (in states /cm^3; my answer in m^3 is to the 10^25), but that's not correct. I'm quite confused as I believe I've put it in correctly.

    Besides doing the calculation over again, I was wondering if there was a relationship between the electron state density and the hole state density that might allow me to approximate? I know the temperature differs by 2K.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook