Difference between valence band and conduction band

            Generally the valence band and conduction band concept comes into picture during the discussion of semiconductors. These concepts also come in the case of conductors and insulators, but in the conductors the valence band and conduction band are said to be merged and there is no difference between the two, while in the case of insulators the valence band and conduction band are at greater distance and no charge transfer takes place between them.

The valence band is the outer most band of the atom where the bonding takes place between two similar or dissimilar atoms and molecules are formed or different elements are formed. The charge carriers in the mainly electrons present in this band are the bonded electrons. In semiconductors specially P-Type the electrons in the valence band takes place in conduction process in the name of the Hole. So P type semiconductor valence band has free charge carriers ( As a result of generation and recombination in the valence band)  and conduction takes place in the valence band

The conduction band is where when the bonding takes place and if any charge carrier is not in the control of its nucleus are roams around the material but within the material and is said to be free charge carrier and takes place in the conduction process. In semiconductors, the additional charge carriers which are not in the vicinity of their nucleus is found in the N Type semiconductors. The conduction process takes place in the conduction band in the N Type semiconductor.

The important aspect to consider is the valence exists and the conduction band is an imaginary band which is assumed to develop the concept of the semiconductor physics and which is found to be in good resemblance with practical results

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