Question

To obtain p-type Si semiconductor, we need to dope pure Si with

• A. Oxygen
• B. Aluminium
• C. Phosphorous
• D. Germanium

Hint:

- p-type → Trivalent impurity (creates holes) - n-type → Pentavalent impurity (adds electrons)

Answer 1

The Correct Option is B

Concept: A p-type semiconductor is formed by doping pure silicon with trivalent impurities (having 3 valence electrons). These impurities create holes as the majority charge carriers.

Step 1: Understand doping for p-type.

• Trivalent atoms (Group 13) → create holes
• Examples: Boron, Aluminium, Gallium

Step 2: Analyze given options.

• Oxygen → not suitable dopant
• Aluminium → trivalent impurity (correct)
• Phosphorous → pentavalent (used for n-type)
• Germanium → tetravalent (same as Si)

Step 3: Final conclusion.
Thus, p-type silicon is obtained by doping with: \[ Aluminium \]