Question

Enunciate the difference between the conductors and semiconductors on the basis of energy bands in solids.

Hint:

The key difference lies in the energy band structure: conductors have overlapping conduction and valence bands, while semiconductors have a small energy gap between the two bands.

Answer 1

The difference between conductors and semiconductors can be explained on the basis of their energy band structure, which refers to the ranges of energy that electrons can occupy within a solid. The key differences are:
1. Conductors:
- In conductors, the conduction band and valence band overlap, allowing free movement of electrons. This overlap means that electrons in the valence band can easily move to the conduction band even at low temperatures.
- There is no energy gap between the valence band and the conduction band. As a result, conductors allow the flow of electric current under an applied electric field.
- Example: Metals like copper, silver, and aluminum.
2. Semiconductors:
- In semiconductors, the valence band and the conduction band are separated by a small energy gap called the band gap. Electrons in the valence band need to gain energy to jump to the conduction band. At absolute zero, no electrons are in the conduction band, but at higher temperatures, some electrons gain enough energy to move to the conduction band and conduct electricity.
- The energy gap between the valence band and conduction band is relatively small (around \(1~\text{eV}\)), which is why semiconductors conduct electricity under certain conditions (e.g., with temperature or doping).
- Example: Silicon, Germanium.