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 an area devoid of mobile charge carriers, formed by electron-hole recombination at the p-n junction. The thickness of this layer is variable and influenced by multiple factors.

Explanation:
The statement that the depletion layer's thickness in a semiconductor diode is not constant is accurate. This thickness is altered by the diode's biasing conditions, which involve applying a voltage across it:

• Forward Bias: Applying a forward bias (positive voltage to the p-type material) causes the depletion layer to shrink. The applied voltage lowers the junction's potential barrier, facilitating charge carrier recombination.
• Reverse Bias: Under reverse bias (positive voltage to the n-type material), the depletion layer expands. The external voltage elevates the barrier potential, widening the depletion region and impeding charge carrier recombination.

The provided reason states that the thickness is contingent on various factors, including biasing. This is correct and serves as a valid explanation for the initial assertion, as biasing directly impacts the formation and variation of the depletion region.

Consequently, the appropriate selection is: If both Assertion and Reason (R) are true and Reason (R) is the correct explanation of Assertion.