Distinguish between conductor and semiconductor on the basis of their energy bands.

Explanation

Conductors: Conductors have resistivity less than `10^(-8)` ohm- m. In such substances the valence band and conduction band overlap each other so that electrons from valence band can easily pass into conduction band. Electrons in the overlapping region are conduction electron.
Semiconductor: In semiconductors, the energy gap is neither too large nor too small, it is of the order of 1eV. At room temperature, i.e., 300K, some electrons in the valence band may have enough thermal energy to surmount the valence band due to the shift of an electron to the conduction band is called a hole. Thus is such solids both electrons and holes contribute to the conduction process and such solids are called semiconductors. Their resistivity varies from `10^(-8)` to `10^(-4)` ohm-m. Energy gap `E_(g)` for Si is 1.12eV and for Ge, it is 0.75 eV.