Question

In the energy band diagram of solids, if the conduction band and the valance band overlap, the solid is

• A. an elemental semiconductor
• B. a metal
• C. an insulator
• D. an inorganic semiconductor

Hint:

Overlap = No gap. No gap = Infinite easy supply of charge carriers = Metal.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Solids are classified into conductors, semiconductors, and insulators based on the energy gap (\(E_g\)) between the valence band and the conduction band.

Step 2: Detailed Explanation:
1. Conductors (Metals): The conduction band and the valence band overlap, or the conduction band is partially filled. Electrons can easily move to higher states, providing high conductivity.
2. Insulators: There is a large energy gap (typically \(> 3\) eV). Electrons cannot jump from the valence band to the conduction band.
3. Semiconductors: There is a small energy gap (typically \(< 3\) eV). Electrons can cross the gap at higher temperatures.
Since the question specifies overlapping bands, the solid must be a metal (conductor).

Step 3: Final Answer:
The solid is a metal.