Question

Which one of the following statements is true for an intrinsic semiconductor?

• A. Electrical conductivity increases with increasing temperature and pressure
• B. Electrical conductivity increases with increasing temperature and decreasing pressure
• C. Electrical conductivity increases with decreasing temperature and increasing pressure
• D. Electrical conductivity increases with decreasing temperature and pressure

Hint:

For intrinsic semiconductors, conductivity mainly depends on bandgap. Anything that reduces the bandgap (like high pressure or high temperature) increases conductivity.

Answer 1

The Correct Option is A

In an intrinsic semiconductor, the number of charge carriers is governed by the energy gap and the thermal excitation of electrons. As temperature increases, more electrons gain enough energy to jump from the valence band to the conduction band, causing conductivity to increase.
Pressure also affects the bandgap: increasing pressure generally reduces the bandgap for intrinsic semiconductors such as Si or Ge. A smaller bandgap means electrons require less energy to transition into the conduction band, resulting in increased electrical conductivity.
Therefore, both increasing temperature and increasing pressure enhance the electrical conductivity of an intrinsic semiconductor, making option (A) correct.