What is the difference between intrinsic semiconductor and extrinsic semiconductor?

What is the difference between intrinsic semiconductor and extrinsic semiconductor? Correct Answer Intrinsic semiconductor is the pure semiconductor and extrinsic semiconductor is conductor with some impurity.

CONCEPT:

• Intrinsic Semiconductor: The intrinsic semiconductor is a pure semiconductor.
  • Since they are pure semiconductors they have the same number of holes and electrons.
  • The conductivity of an intrinsic semiconductor is very low at room temperature.
• Extrinsic Semiconductor: We add a small amount of impurity to the pure semiconductor.
  • This increases the conductivity of the semiconductor by manifold.
  • This impure semiconductor is called an extrinsic semiconductor.

EXPLANATION:

• Option 1: The conductivity of an intrinsic semiconductor is very low at room temperature. It means very low or no current flows at room temperature.
  • So this is an incorrect statement.
• Option 2: Since intrinsic semiconductors are pure semiconductors they have the same number of holes and electrons. 
• Option 3 and 4: The intrinsic semiconductor is a pure semiconductor and an extrinsic semiconductor is a semiconductor with impurity.
  • So option 4 gives the correct statement.
• So the correct answer is option 4.