Drift vs Diffusion current

  1. In a forward-biased PN junction, the potential barrier decreases, allowing more majority carriers from one side to diffuse to the other side where they are minority carriers. After they cross the potential barrier, they form a diffusion current, the drift current of minority carriers is insignificant, then they recombine with majority carriers and form a drift current under the effect of the applied electric field.

    Why do minority carriers form a diffusion current not a drift current after they cross the potential barrier? It is counter-intuitive that the main current is diffusion when there is an applied electric field.

    This is according to all the microelectronics book I'm currently reading. There is one which says this can be proved but without providing anything. Can someone please provide a proof for this.
  2. jcsd
  3. dlgoff

    dlgoff 3,147
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    2014 Award

    This is a good read on Transistor Action.

  4. I have went through the link you provided, but this doesn't touch on the question.
    Maybe this thread is more solid-state physics than electrical engineering !?
  5. maybe you'd like to borrow a book :tongue:

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  6. lol, it may be the only way.
    I'm actually reading through Sedra 5th edition on this matter, it states the current is a diffusion current but without giving the reasons. It seems electrical engineering books leave many holes when describing the physics of the devices
  7. dlgoff

    dlgoff 3,147
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    2014 Award

    You went through all that? Did you go through their links

    Semiconductor concepts and Semiconductors for electronics
  8. Yes, I've been scanning this site for the past couple of weeks.
    Most of the sites I've read seem to describe the operation of the PN junction or the diode, but I'm unable to find the answer to this specificity.
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