Question

In an n-type semiconductor, the Fermi-energy level lies :

• A. in the forbidden energy gap nearer to the conduction band
• B. in the forbidden energy gap nearer to the valence band
• C. in the middle of forbidden energy gap
• D. outside of the forbidden energy gap

Answer 1

The correct option is A in the forbidden energy gap nearer to the conduction band

For an n-type semiconductor, there are more electrons in the conduction band than there are holes in the valence band. This is due to the doping of donor impurity to form n-type semiconductor. This leads to formation of donor energy level below conduction band in forbidden energy gap, which implies that the probability of finding an electron near the conduction band edge is larger than the probability of finding a hole at the valence band edge. Therefore, the Fermi level is closer to the conduction band in an n-type semiconductor and it lies in the forbidden energy gap nearer to the conduction band.