Question

In case of semiconductors, the band gap between the valence band and conduction band is

• A. between \(5\ \text{eV}\) and \(6\ \text{eV}\).
• B. between \(10\ \text{eV}\) and \(11\ \text{eV}\)
• C. \(1\ \text{eV}\) or less but greater than zero.
• D. zero.

Hint:

A semiconductor has a small but non-zero gap between valence and conduction bands, about 1 eV or less.

Answer 1

The Correct Option is C

Step 1: Eliminate large gaps
Gaps of $5$-$6\ \text{eV}$ or $10$-$11\ \text{eV}$ belong to insulators, where electrons cannot be excited easily.

Step 2: Eliminate zero gap
A zero gap means the bands overlap, which is the case for metals.

Step 3: Conclusion
So the semiconductor gap is small but non-zero, about $1\ \text{eV}$ or less.

Final Answer:
A semiconductor has a small non-zero gap of about 1 eV or less. \[ \boxed{\text{(C) }1\ \text{eV or less but greater than zero.}} \]