PN junction Forward-bias help

Discussion in 'General Electronics Chat' started by Digin8918, Nov 8, 2009.

  1. Digin8918

    Thread Starter New Member

    Sep 5, 2009
    I had such good replies to my previous question on another thread, I decided to start another to see what else I can milk out of you fine people :). My question is about the forward-bias of a PN junction in semiconductors and diodes. I have a link here to a website that attempts to explain the way a diode works, but I suppose it is not necessary for anyone that already knows about them,,
    If you go to this and navigate back a couple of times you can get all of the relevant information that I have been looking at. I've also read the full description of PN junction on wikipedia which also confuses me to some extent. What I do not understand is that when you add an external voltage in the forward-bias configuration to a PN junction, how is there a net current going from P to N? The holes in the P-type are repelled by the positive battery pole, and the electrons in the N-type are repelled by the negative battery pole, and then the holes and electrons meet in the middle, and penetrate a short distance into each other before recombining. When wikipedia describes this, it says something to the effect that even though they recombine in the middle, the current remains uninterrupted. I got an idea that because the electrons recombine going towards the P-region, that they leave behind holes that flow going back all the way through the N-region? But, even if that is the case, why is there a net current flowing from P to N? Please someone attempt to explain this to me. I feel that I understand all the doping stuff and P-types and N-types, but I just don't seem to know how to put it together to fully understand forward-bias. Also, is one side more doped than the other, or are they equally doped? I appreciate people's willingness to help others on here, and I'd like to say thank you for that and for reading this post.