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Homework Help: Semiconductor Physics

  1. Mar 30, 2013 #1
    1. The problem statement, all variables and given/known data
    A certain doped semiconductor at room temperature has the following properties: no = 9 x 1014 / cm3, po = 4 x 1014 / cm3, μe = 800 cm2 / V-s, μh = 400 cm2 / V-s, and (Dh[itex]\tau[/itex]h)1/2 = 10-4 cm.

    If an electric field is applied, what fraction of the resulting drift current flow will be due to electrons?

    2. Relevant equations
    Not sure.

    3. The attempt at a solution
    I have no idea what to do, but the answer is 0.82 (according to the book).
  2. jcsd
  3. Mar 30, 2013 #2
    Could you perhaps state what you think all the letters mean?

    I would guess that:
    No is charge carrier density of n type
    p is charge carrier density of p type
    no idea what μ e and h are ... or what Dh and Tau h are,

    In my experience (if this came from a lecturer) he will have given you a formula. Perhaps even with all these terms present.. and the answer may just fall out....

    I found this related PDF
    http://users.ece.gatech.edu/~alan/ECE3080/Lectures/ECE3080-L-7-Drift - Diffusion Chap 3 Pierret.pdf

    It contains equations for calculating hole and drift currents (if you have the right parameters available).

    Maybe if you worked out the hole current , worked out the drift current ... and divided one by the other to get the ratio?

    Sorry its not a complete answer but it may get you going in the right direction :)
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