Question

Choose the correct statement

• A. An intrinsic semiconductor has trivalent or pentavalent impurities.
• B. Pure Ge or Si is an extrinsic semiconductor.
• C. The conductivity of a semiconductor can be increased by reducing its temperature.
• D. A rectifier circuit does not use p-n junction diodes.
• E. The potential barrier in a forward biased p-n junction gets reduced

Hint:

Forward Bias \(\rightarrow\) Barrier Height Reduces \(\rightarrow\) Current Increases.
Reverse Bias \(\rightarrow\) Barrier Height Increases \(\rightarrow\) Current Decreases.

Answer 1

Answer: (E)

Step 1: Understanding the Concept:
This question tests basic knowledge of semiconductor physics and p-n junctions.

Step 2: Detailed Explanation:
1. Statement A: Incorrect. Intrinsic semiconductors are pure. Semiconductors with impurities are called extrinsic.
2. Statement B: Incorrect. Pure Ge/Si are intrinsic semiconductors.
3. Statement C: Incorrect. In semiconductors, conductivity increases as temperature increases (negative temperature coefficient of resistance).
4. Statement D: Incorrect. Rectifiers are primary applications of p-n junction diodes.
5. Statement E: Correct. In forward bias, the external voltage opposes the potential barrier, narrowing the depletion region and reducing the barrier height.

Step 3: Final Answer:
The potential barrier in a forward biased p-n junction gets reduced.