Given below are two statements:
Statement (I) : Adding a chemical impurity to a pure semiconductor is called doping.
Statement (II) : A semiconductor in an extremely pure form is known as an extrinsic semiconductor.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Statement I is true but Statement II is false
A semiconductor such as pure silicon or germanium conducts only a little. Its conductivity is raised by adding a tiny, controlled amount of another element, and the two kinds are named for this: intrinsic (pure) and extrinsic (with impurity added).
Statement (I): Adding a chemical impurity to a pure semiconductor is called doping. Correct. This is the definition of doping. Adding a pentavalent element such as phosphorus gives an n-type semiconductor, and a trivalent element such as boron gives a p-type semiconductor.
Statement (II): A semiconductor in an extremely pure form is known as an extrinsic semiconductor. Incorrect. A semiconductor in its extremely pure form is an intrinsic semiconductor. An extrinsic semiconductor is the doped one, the very opposite of pure.