Question

In case of a p-n junction diode at high value of reverse bias the current rises sharply. The value of reverse bias is known as:
(A) Cut-Off Voltage
(B) Zener Voltage
(C) Inverse Voltage
(D) Critical Voltage

Answer 1

Hint: In a reverse biased diode, current does not flow until the electric field strength of the depletion layer exceeds a certain value. In a reverse biased p-n diode, when the electric field enables tunnelling of electrons from the valence to the conduction band of a semiconductor, it leads to numerous free minority carriers which suddenly increase the reverse current.

Complete Answer:
Reverse bias usually refers to how a diode is used in a circuit. If a diode is reverse biased, then the voltage at the cathode is higher than that at the anode.
Therefore, no current flows.
It has been given that, in case of a p-n junction diode at high value of reverse bias the current rises sharply.
In a reverse-biased diode, the p-type material is connected to the negative side of the applied voltage. Hence, the holes in the p-type material are pulled away from the junction, causing the thickness of the depletion layer to increase.
Similarly, because the n-type region is connected to the positive side, the electrons will also be pulled away from the junction. Therefore as the depletion layer widens, the reverse-bias voltage shall increase. This increases the voltage barrier causing a high resistance to the flow of charge carriers thus allowing only a very small electric current to leak across the PN junction.
Current starts to flow once the strength of the depletion layer electric field exceeds the threshold value, and the P-N junction depletion layer no longer exists.
This effect is used to one's advantage in zener diode regulator circuits. Zener diodes have a well-defined low reverse breakdown voltage by design. The current increases tremendously because the number of charge carriers increases so much that zener breakdown occurs at such high negative voltages.
Hence the correct option is Option B.

Note:
The Zener or avalanche breakdown processes are non-destructive and are reversible, as long as the amount of current flowing does not reach levels that cause the semiconductor material to overheat and cause thermal damage.
A typical value for the breakdown voltage is $6.2V$. This means that the voltage at the cathode can never be more than $6.2V$ higher than the voltage at the anode, because the diode will break down, and therefore conduct, if the voltage gets any higher. This effectively limits the voltage across the diode.