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Electrical Engineering
What Explains the Lack of Current in a PN Junction at Equilibrium?
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[QUOTE="unified, post: 6554156, member: 400921"] [B]TL;DR Summary:[/B] I am considering a PN junction at equilibrium, and have a couple of questions. Consider a PN junction doped with say phosphorous on the N side, and Boron on the P side. Initially, there is an opportunity for the electrons just below the N conduction band to drop to the lower available energy states just above the P valence band. This leaves the N side positively charged and the P side negatively charged, forming a depletion region. This means that there will be an electric field pointing in the direction from N to P. Eventually, there will be an equilibrium that is reached, in which case there is no current in the depletion region. I do not know which of the following explains why there is no current in the depletion region under equilibrium. 1. The electric field causes electrons from the negatively charged P side to flow back to the N type, and in equilibrium this cancels the flow of electrons from N to P. Also, the electric field causes holes to flow from N to P, and this cancels any holes flowing from P to N. The result of these processes is zero net current. 2. There is no current flowing either from N to P or P to N in equilibrium. In equilibrium, the depletion region is essentially an insulator, and while we have an electric field present in the region, the charge is not free to flow. [/QUOTE]
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What Explains the Lack of Current in a PN Junction at Equilibrium?
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