Question

Semiconductor without any impurities are called

• A.
  Intrinsic Semiconductor
• B.
  Extrinsic Semiconductor
• C.
  n-type semiconductors
• D.
  p-type semiconductor

Answer 1

The correct option is A

Intrinsic Semiconductor
The conduction by pure substances such as silicon and germanium exhibiting electrical conductivity are called intrinsic semiconductors.

Atoms of $Si$ and $Ge$, both have four electrons in their outer shell.
At very low temperatures, the valence band is filled and the conduction band is empty in $Si$ and $Ge$.
Under these conditions, $Si$ and $Ge$ are both insulators, and cannot carry any electric current.
The conductivity of pure silicon and germanium is low at room temperature, so, to increase the conductivity the process doping comes.