The function of a donor in extrinsic semi-conductor is to:

Question

Question

Answer 1

CONCEPT:

Doping: The process of adding impurities to a pure (intrinsic) semiconductor is called doping.
- By doing this, the conductivity of the semiconductor is increased drastically even at room temperatures.
- It is needed because the conductivity of a pure semiconductor like silicon or germanium is very low at room temperatures.
- Doping leads to the formation of extrinsic semiconductors which are of two types: n-type and p-type.
N-type semiconductors have impurities of elements from Group 5 of the periodic table, hence electrons are the majority charge carriers.
P-type semiconductors have impurities of elements from Group 3 of the periodic table, hence holes are the majority charge carriers.

EXPLANATION:

The elements whose atom has five valance electrons are called pentavalent impurities e.g. As, P, Sb, etc.
These impurities are also called donor impurities because they donate an extra free electron.
Thus, the n-type semiconductor is obtained if we dope Silicon with a pentavalent element.