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Mobility of holes and electrons

  1. May 15, 2008 #1
    hi,
    holes are the absence of electrons in the lattice, right? then how come we say holes have a +ve charge? shouldnt it be zero?
    also, why is the mobility of electrons more than holes?
    thanks
     
  2. jcsd
  3. May 15, 2008 #2

    Defennder

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    This is what I wrote for another thread:

    As for the other question, I'm guessing it's something to do with the magnitude of their effective masses.
     
  4. May 15, 2008 #3
    i should ve searched for that before posting a new thread. it makes sense, yes..

    what would the effective mass of a hole be??
     
  5. May 15, 2008 #4
    Where would you usually find a hole? And where would you usually find an electron?

    Where == which band?

    Yes, the effective masses of holes and electrons are different. The mobility is a function of the effective mass, which is a theoretical tool brought in to simplify the description of a charged particle in a crystal. Classically, the concept of an effective mass is analogous to that of a 'psuedo force' in Newtonian mechanics.

    In the simplified, Drude model, the mobility is inversely proportional to the effective mass, for a fixed mean free time.
     
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