Question

In an intrinsic semiconductor, conductivity is:
A. Low at room temperature
B. Average
C. High at room temperature
D. Zero at room temperature

Answer 1

Semiconductors are of two types one is intrinsic semiconductors and another one is extrinsic semiconductors. The pure form of semiconductors is known as intrinsic semiconductors and the semiconductors in which impurities are added intentionally for making it conductive is known as extrinsic semiconductors.

Complete step by step answer:
There are three bands in a semiconductor one is valence band, Conduction band and forbidden energy band gap. The conduction of electrons will happen when the electrons go from the valence band to the conduction band. Energy is required by electrons to go from the valence band to the conduction band and this energy is supplied in the form of heat. Conductivity in semiconductor is given by:
$\sigma = nq{\mu _e}$;
Where:
$\sigma$= Conductivity;
n = Temperature;
${\mu _e}$= Electron mobility;
So, by the above equation as the temperature of the semiconductor increases so does its conductivity. The room temperature is around 20 – 22 degree Celsius, that means there is some heat available, that means that at room temperature the conductivity of the intrinsic semiconductor will be Low.

Hence, the correct answer is option (A).

Note: Here, we need to explain semiconductors and its type and also, we need to explain about the types of band present in the semiconductor and what happens to the electrons when they move from valence band to the conduction band. Explain the dependency of the temperature on conductivity of the semiconductors. In conductors it is opposite, the more the resistance is the more it’s temperature.