Question

When Boron is added as impurity to silicon, semiconductor becomes:

• A. N type semiconductor.
• B. P type semiconductor.
• C. PN junction.
• D. None of the above.

Hint:

When Group III elements like Boron are added to silicon, it results in a P-type semiconductor due to the creation of holes (positive charge carriers).

Answer 1

The Correct Option is B

Step 1: Understanding the concept.
When Boron (a Group III element) is added to silicon (a Group IV element) as an impurity, it creates "holes" (missing electrons) in the crystal structure, which makes the silicon a P-type semiconductor. This is because Boron has one less electron than silicon, and this creates an excess of positive charge carriers (holes).
Step 2: Analyzing the options.
(1) N type semiconductor: This is incorrect. An N-type semiconductor is created by adding Group V elements like Phosphorus, which contribute extra electrons (negative charge carriers).
(2) P type semiconductor: Correct. Adding Boron to silicon results in a P-type semiconductor due to the creation of holes (positive charge carriers).
(3) PN junction: This is incorrect. A PN junction is formed when both P-type and N-type semiconductors are combined, not by adding a single impurity.
(4) None of the above: This is incorrect, as option (2) is the correct answer.
Step 3: Conclusion.
The correct answer is (2) P type semiconductor, as Boron creates holes that make silicon a P-type semiconductor.