Question

Assertion : In a semiconductor diode, the thickness of the depletion layer is not fixed.

Reason (R): Thickness of depletion layer in a semiconductor device depends upon many factors such as biasing of the semiconductor.

• A. If both Assertion and Reason (R) are true and Reason (R) is the correct explanation of Assertion .
• B. If both Assertion and Reason (R) are true but Reason (R) is not the correct explanation of Assertion .
• C. If Assertion is true but Reason (R) is false.
• D. If both Assertion and Reason (R) are false.

Hint:

In a semiconductor diode, the depletion region's thickness changes with biasing. Reverse bias increases it, and forward bias decreases it.

Answer 1

The Correct Option is A

In a semiconductor diode, the depletion layer is a region where mobile charge carriers are absent due to the recombination of electrons and holes. This layer forms at the junction between the p-type and n-type materials. The thickness of this depletion layer is not constant and varies depending on several factors.

Explanation:
The assertion states that in a semiconductor diode, the depletion layer's thickness is not fixed. This is true. The thickness of the depletion layer can change due to the biasing of the semiconductor. Biasing refers to applying voltage across the diode:

• Forward Bias: When the diode is forward-biased (positive voltage is applied to the p-type material), the depletion layer narrows. This occurs because the external voltage reduces the junction's barrier, allowing charge carriers to recombine more easily.
• Reverse Bias: In reverse bias (positive voltage is applied to the n-type material), the depletion width increases. The external voltage increases the barrier potential, widening the depletion region and preventing charge carrier recombination.

The reason given is that the thickness depends on various factors, such as biasing. This is true and explains the assertion since biasing directly affects how the depletion region forms and changes.

Therefore, the correct choice is: If both Assertion and Reason (R) are true and Reason (R) is the correct explanation of Assertion.