Explanation

when a donor impurity interacts with a pure crystal, it leads to the formation of an n-type semiconductor.

Concept:

The process of deliberate addition of a desirable impurity to a pure semiconductor so as to increase its conductivity is called doping

The impurity atoms added are called doped. 

Semiconductors doped with the impurity atoms are called extrinsic.

Explanation:

The element whose atom has five valance electrons are called pentavalent impurities e.g As, P, Sb, etc

These impurities are called donor impurities because they donate an extra free electron.

The semiconductor material with the majority carrier as the electron is called an n-type semiconductor