Conductors:
In the case of conductors,there is no forbidden band and the valence band and conduction band overlap each other.Here plenty of force electrons are available for electric conduction. The electrons from valence bond freely enter in the conduction band.The most important point in conductors is that due to absence of forbidden band, there is no structure to establish holes. The total current in conductors is simply a flow of electrons.
Semi-conductors:
In the semi-conductors,the forbidden band is very small. Germanium and silicon are example of semi-conductors. In the germanium forbidden band is of the order of 0.7ev while in case of silicon, the forbidden band is of material is one 1ev.Actually,a semi-conductor material is one whose electrical properties lies between insulators and good conductors.At zero degree kelvin there are no electrons in conduction band and the valence band is completely filled. When a small amount of energy is supplied, the electrons can easily jump from valence band to the conduction band.For example, when the temperature is increased,the forbidden band is decreased so that some electrons are liberated into the conduction band .In semi-conductors,the conductivities are of the order of 10^2mho-metere.
In the case of conductors,there is no forbidden band and the valence band and conduction band overlap each other.Here plenty of force electrons are available for electric conduction. The electrons from valence bond freely enter in the conduction band.The most important point in conductors is that due to absence of forbidden band, there is no structure to establish holes. The total current in conductors is simply a flow of electrons.
Semi-conductors:
In the semi-conductors,the forbidden band is very small. Germanium and silicon are example of semi-conductors. In the germanium forbidden band is of the order of 0.7ev while in case of silicon, the forbidden band is of material is one 1ev.Actually,a semi-conductor material is one whose electrical properties lies between insulators and good conductors.At zero degree kelvin there are no electrons in conduction band and the valence band is completely filled. When a small amount of energy is supplied, the electrons can easily jump from valence band to the conduction band.For example, when the temperature is increased,the forbidden band is decreased so that some electrons are liberated into the conduction band .In semi-conductors,the conductivities are of the order of 10^2mho-metere.
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