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What is the doping and hole concentration?

  1. Apr 27, 2015 #1
    1. The problem statement, all variables and given/known data

    (a) Show law of mass action.
    (b) Find dopant concentration and hole concentration.

    2012_B6_Q3.png

    2. Relevant equations


    3. The attempt at a solution

    Part(a)

    Bookwork.

    Part(b)

    Letting the doping concentration be ##D##, we have:
    [tex]D = n - p[/tex]
    For ##I = n_{intrinsic} = p_{intrinsic}##, we have:
    [tex]D^2 + 4I^2 = (n+p)^2 = (n-p)^2 + 4np[/tex]

    Which gives us the result
    [tex]n = \frac{1}{2}\left( \sqrt{D^2 + 4I^2} + D \right) [/tex]
    [tex]p = \frac{1}{2}\left( \sqrt{D^2 + 4I^2} - D \right) [/tex]

    For the doping to work at 750K, I estimate the doping concentration to be ##D \approx n_{intrinsic} = \sqrt{np}##.
    At 750 K,
    [tex]D = \sqrt{np} = 1.7 \times 10^{23}[/tex]
    At 300K,
    [tex]I = \sqrt{np} = 1 \times 10^{19} [/tex]

    Since ##D >> I##, we have
    [tex]p \approx \frac{I^2}{D} = 6 \times 10^{14} [/tex]

    Is this right?
     
  2. jcsd
  3. May 2, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
     
  4. May 4, 2015 #3
    bumpp
     
  5. May 7, 2015 #4
  6. May 10, 2015 #5
    bumpp dope
     
  7. May 14, 2015 #6
    bumping on dope
     
  8. May 16, 2015 #7
    bumping dope concentration?
     
  9. May 18, 2015 #8
    bump on dopant concentration
     
  10. May 22, 2015 #9
  11. May 23, 2015 #10
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