Question

Which one of the following elements when doped with silicon makes it p-type semiconductor ?

• A. As
• B. Bi
• C. Ga
• D. Sb

Hint:

A p-type semiconductor needs a trivalent (group 13) dopant, which creates holes.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
Silicon has four valence electrons. A p-type semiconductor is made by adding a trivalent impurity from group 13.

Step 2: Why
Each trivalent atom forms only three bonds, leaving an electron vacancy (hole) that carries current.

Step 3: Compare the options
As, Sb and Bi are group 15 elements with five valence electrons, so they give n-type material.
Gallium is in group 13.

Final Answer:
Doping silicon with gallium gives a p-type semiconductor. \[ \boxed{\text{(C) }\text{Ga}} \]