Question

In a semiconductor, the forbidden energy gap between the valence band and the conduction band is of the order is

• A. $1MeV$
• B. $0.1MeV$
• C. $1eV$
• D. $5eV$

Answer 1

Answer: (C)

Forbidden energy gap, also known as band gap refers to the energy difference $\left(eV\right)$ between the top of valence band and the bottom of the conduction band in materials. Current flowing through the materials is due to the electron transfer from the valence band to the conduction band.

As the electrical conductivity of semiconductors lies between the conductors and the insulators, thus a small but non-zero bandgap $(\approx 1eV)$ occurs in the semiconductors.

Example: Bandgap in silicon and germanium is $1.11eV$ and $0.67eV$ respectively.