When the temperature of an extrinsic semiconductor increases, the pronounced effect is on________
Right Answer is:
Minority carriers
SOLUTION
When the temperature of an extrinsic semiconductor increases, the pronounced effect is on Minority carriers.
Detailed Explanation
⇒ When the temperature of an n-type semiconductor is raised, the number of electron-hole pairs due to thermal excitation from the valence band to the conduction band will increase.
From the figure, the following points can be deduced. (Tc= Curie temperature.)
1. At T= 0 Kelvin: The carrier concentration is zero hence, conductivity is zero and extrinsic semiconductor will be working as an insulator.
2. At O Kelvin < T < 300K: As temperature increases, majority and minority carriers are created and thus conductivity of extrinsic semiconductors increases with temperature.
3. At T= 300 Kelvin: The conductivity of extrinsic semiconductors will become maximum.
4. At 300K < T < Tc
(i) As temperature increases, the mobility of the charge carrier and, therefore, conductivity increases.
(ii) As temperature increases, the majority carrier concentration will remain almost constant.
(iii) As temperature increases, minority carrier concentration increases with the temperature.
5. At T= TC (Curie temperature): The concentration of minority carriers becomes equal to majority carrier concentration and therefore, extrinsic semiconductor will become intrinsic and the conductivity will be minimum.
6. At T > Tc The semiconductor is now intrinsic and conductivity increases with the temperature.
7. At very high temperatures, extrinsic semiconductors will behave as intrinsic semiconductors (at Curie temperature).
8. At low temperatures, the conductivity of extrinsic semiconductors increases with temperature (below 300 K).
9. At Curie temperature, extrinsic semiconductor becomes intrinsic.
10. In an extrinsic semiconductor, as the temperature is increased (above 300K), its conductivity decreases.
Note: Majority carrier concentration remains constant as temperature increases while minority carrier concentration increases with temperature Majority carrier concentration is almost independent of temperature.