Question

What is a pure and impure semiconductor?

Answer 1

Semiconductors are materials that have a conductivity between conductors and non-conductors or insulators.

Pure semiconductor: A pure or intrinsic type of semiconductor material is made to be very pure chemically. Germanium (Ge) and Silicon (Si) are the most common type of pure semiconductor elements.

1. In other words, free from impurities are termed as intrinsic semiconductors or pure semiconductors. The number of holes and electrons is therefore determined by the properties of the material itself instead of the impurities.
2. In intrinsic semiconductors, the number of excited electrons is equal to the number of holes; n = p.

Impure semiconductor: An impure or extrinsic semiconductor material is made by doping trivalent or pentavalent elements with the pure semiconductor.
There are two types of impure semiconductors:
1. p-type semiconductor: In p-type semiconductors, the holes are the majority carriers.
2. n-type semiconductor: In n-type semiconductors, the electrons are the majority carriers.