Classification of solids on band theory
Solids can be classified under following categories based on band theory:
Conductors:
Metals are conductors in which there is no forbidden energy gap between the conduction band (CB) and valence band (VB). No extra energy required to transfer the electron from VB to CB.
Semiconductors:
In a semiconductor, the valence band is completely filled with electrons while the conduction band is empty. The energy gap between the bands is less. For electrons to jump from the valence band to the conduction band, room temperature needs to be maintained. If the temperature is 0K, there is no transfer of electrons from the valence band to the conduction band.
Insulators:
In insulators, the valence band is completely filled while the conduction band is empty. This results in a large energy gap. Since the energy gap between the conduction band and the valence band is more, there is no movement of electrons from the valence band to the conduction band.
