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MOSCAP band diagram question

  1. May 5, 2012 #1
    I've been looking over MOS capacitors lately and I have a few questions I haven't been able to answer myself.

    Whenever you apply a voltage to the metal I do not understand why the conduction and valence bands for the semiconductor move, but the fermi level does not.

    Also whenever you apply a voltage why does the oxide line change.

    I think really I'm not quite sure I fully understand what the energy lines represent (Ec,Ev, oxide energy line). I know that Ec is the energy an electron needs to be at to be a free carrier and Ev is where you have holes, but by accumulating some charge at the surface of the semiconductor, why would the energy needed to be a carrier change too?

    I'll try and clarify my questions as I go, right now this is the best I can ask them.

  2. jcsd
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