What is a P-N junction and how does it work?
Well, a P-N Junction is the boundary between the two semiconductor metals known as the p type and the n type. The n-type is created by doping a silicon atom with small amounts of Antimony, and a p-type is made by doping another silicon atom with small amounts of Boron. When they make contact they behave differently than they do by themselves and create one semiconductor that has been doped differently on either side. In particular, the current will only flow through it in one direction (forward or reversed bias). The lattice between the two metals (diffusion region) have holes in them that when filled with electrons cancel each other and vanish. This causes an area which is depleted of any moving charges called the "depletion zone" and this transfer of electrons occurs on both sides creating an equilibrium. When a free charge enters the depletion zone it does not see any other free charges, instead it sees positive charges on the n side and negative charges on the p side. The force that these charges place on the free charge cause it to return to its original spot and leave the depletion zone. As a result the junction acts like a barrier and regulates the current. In order for charges to move from one type to the other they need to use extra energy and "climb uphill". The extra energy required can be supplied by a voltage applied between the two ends of the junction diode. If voltage is applied the wrong way the free charges are pulled away from the junction, causing it to not work.
http://www.electronics-tutorials.ws/diode/diode_2.html
Well, a P-N Junction is the boundary between the two semiconductor metals known as the p type and the n type. The n-type is created by doping a silicon atom with small amounts of Antimony, and a p-type is made by doping another silicon atom with small amounts of Boron. When they make contact they behave differently than they do by themselves and create one semiconductor that has been doped differently on either side. In particular, the current will only flow through it in one direction (forward or reversed bias). The lattice between the two metals (diffusion region) have holes in them that when filled with electrons cancel each other and vanish. This causes an area which is depleted of any moving charges called the "depletion zone" and this transfer of electrons occurs on both sides creating an equilibrium. When a free charge enters the depletion zone it does not see any other free charges, instead it sees positive charges on the n side and negative charges on the p side. The force that these charges place on the free charge cause it to return to its original spot and leave the depletion zone. As a result the junction acts like a barrier and regulates the current. In order for charges to move from one type to the other they need to use extra energy and "climb uphill". The extra energy required can be supplied by a voltage applied between the two ends of the junction diode. If voltage is applied the wrong way the free charges are pulled away from the junction, causing it to not work.
Helpful Links:
http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/comp/passive/diode/pn_junc/pn_junc.htm
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