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How does reverse bias get current.

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Hi everyone,

Can you guy explain to me how does a current flow in a PN when it operated in a reverse bias. What i know is that when apply negative voltage terminal at the P substrate and the positive terminal at the N substrate, the depletion region get increase. Also, the electron in the N substrate can not jump to the Hole in the P substrate. So by theory, there will be no current in a reverse bias mode. However, in a NPN transistor, the current do get flow in a reverse bias condition. Can you explain me this confusion.

Thank you.
 

There will be hole-electron pairs generated in the depletion region from the thermal energy. You will only get no current at absolute zero temperature.
 

In a NPN transistor there is will karge current when compared to a reverse biased PN junction because the reverse bias is only to drive the electrons that have enetered the base where they are minority carriers... this reverse between base and collector drives these electrons that have entered the base in to the collector resulting in large current flow...
 

Thank for the reply. I understand the when apply positive terminal power to the base in a NPN transistor, the depletion region between NP get decrease (while ground emiter). as a result, it NP junction operate at forward biasing (The turn on voltage is 0.7 volt). However, if i also apply positive terminal power to the other N region (the collector, the other half of the NPN), the depletion between the PN junction is increasing. As a result, there should be no current flow between the PN. I look at my lecture note, it claim that most current is flow through there. I am still confuse. can you guy explain.

Thank you.
 

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