Question

The objective of adding impurities in the intrinsic semiconductor is

• A. to increase the conductivity of the semiconductor.
• B. to increase the density of total current carries.
• C. to increase the density of either holes or electrons but not both.
• D. to eliminate the electron-hole pairs produced in intrinsic semiconductor.

Answer 1

Answer: (A), (C)

The correct options are
A to increase the conductivity of the semiconductor.
C to increase the density of either holes or electrons but not both.

In intrinsic semiconductors, $n=p$. Hence, at room temperature, no free electrons are available for conduction. If some impurity (either trivalent or pentavalent) is added to intrinsic semiconductor it will increase the concentration or density of charge carriers (either holes or electrons) and which in turn increase its conductivity.