Question

In a semiconductor, [more than one option may be correct]

• A. there are no free electrons at $0K$
• B. there are no free electrons at any temperature
• C. the number of free electrons increases with temperature
• D. the number of free electrons is less than that in a conductor

Answer 1

Answer: (A), (C), (D)

there are no free electrons at $0K$
the number of free electrons increases with temperature
the number of free electrons is less than that in a conductor

Option A,C and D are correct.

A: At $0K$ all the electrons are in the valence band and no electrons are there in the conduction band.

C: As the temperature increases electrons gain kinetic energy ; break the covalent bonds and move to conduction band as the result number of free electrons and holes increases.

D: The number of free electrons are less as they form a covalent bonds due to which lattice structure is created.

B: At $0K$ there are no free electrons but the number of electrons increases with the increase in temperature.