Question

Why is the current under reverse bias almost independent of the applied potential up to a critical voltage?

Answer 1

At any temperature the number of minority carriers is constant so there is the small current at any applied potential. This is the reason for the current under reverse bias to be almost independent of applied potential.

Thus there is a sudden increase in the current at the critical voltage.

Answer 2

Reason on the current under reverse bias is almost independent:

• There are two conditions in which a diode kept in when working one is "forward biased condition" and the other is the "reverse Biased condition".
• When the diode is working in the "reverse bias", there is a certain point known as the "knee voltage" or "critical voltage up".
• And the application of voltage has no effect in the flow of minority carriers at any temperature until the critical voltage is applied because the number of minority carriers will remain same even if the voltage is increased.
• But after the knee voltage is attained, if there is a breaking of the junction and a certain surge of current is happened.

To know more:

Why are photodiodes preferbly operated under reverse bias when the current in the farword bias known to be more than that reverse bias?

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