Conduction Band In Semiconductors And Metallic Conductors

As we know the concept of the conduction band, these are a different class of energy level band that is not filled with electrons as these are highly mobile and possess electrical conductivity traits. It can also be defined as a range of different energy values found in a given solid material. This trait allows electrons to stay separate from a particular atom and carry an electric charge through the material.

In this article, we will look at conduction bands in semiconductors and metallic conductors in detail to understand their various aspects.

Meaning of conduction band 

Conduction band can be defined as the band of electron orbitals that can skip from a level with low energy to a high energy level upon getting excited. When electrons are present in these orbitals, they possess enough energy to navigate freely. This shift of electrons gives rise to electric current to form a conduction band in semiconductors.

The outermost electron orbital of a given atom present on any material where electrons are occupied creates a valence band. The energy difference between the lowest occupied state and the highest occupied energy state is referred to as the bandgap. It indicates the potential of a material to conduct electricity. It can be concluded that a large bandgap can be identified by its capability to excite valence electrons in the conduction band. 

On the other hand, electrons can easily jump between two different bands when the valence bond and conduction band cross each other, implying that the given material possesses good conductive characteristics.

Band Theory of Solids

According to the band theory of solids, the energy levels of overlapping electron shells are somewhat changed. However, the nearby atoms do not have any influence on the energy level of electrons present in the innermost part. It considered the energy level structures of solid and the resulting formation of energy bonds that consists of several states put close together. This theory also attempts at explaining the quantum state of electrons as it takes place inside a metal solid. Multiple discrete energy levels form a molecule, which is precisely explained about the conduction band in semiconductors by the band theory of solids.

Electrons are present in their respective energy orbits in atoms. Two different atomic orbitals come together and form a molecular orbital with two different energy levels in the case of molecules. However, in the case of solids, several lines are limited in a bit of space, which creates a band forming huge energy chunks called energy bands. 

We can easily visualise the existing differences between semiconductors, insulators, and conductors with the help of this theory, as it helps to understand the available energy meant for electrons present in different materials. Thus, it can be concluded that the band theory of solids provides an insightful explanation of the same. 

Conduction band in semiconductors

Similar to the concept of valence bands, conduction bands are the closest to existing energy levels and help identify a material’s electrical conductivity. The band is the lowest range of empty electronics states in the case of the conduction band in semiconductors and electrical insulators. For instance, if a graph is prepared to show the electronic band structure of a given material, it would be preferable to show the valence bond below the Fermi level with the conduction band placed above the same. 

One conduction band in semiconductors examples that we can take here to understand this better is diamonds. It belongs to the white bandgap semiconductors with great potential and the conductor and electronic device material. On the other hand, germanium will need to operate the resulting differences in temperatures as it has relatively small bandgap energy. The differences between the conduction band and valence do not hold any meaning in the case of metals. It is because conduction takes place only in the case of partially filled bands based on the properties of both conduction band and valence band. 

Conduction band in metallic conductors

In the case of metallic conductors, there is no gap between conduction bands because metals are conductors and the two factors overlap at some point. It is also important to note that it facilitates a continuous supply of electrons in the existing orbitals that are spaced closely. Thus, we can conclude that no gap is found between their balance and collection bands due to the two entities overlapping.

Conclusion 

In a nutshell, it can be concluded that conduction bands appear in different forms on different levels in semiconductors and metallic solids. In the case of materials classified under the category of semiconductors, there is almost no conduction band due to the presence of the valence band. It also relates deeply to the band structure of semiconductor and metallic materials to help us understand conduction bands in semiconductor’s importance.

One has zero band gaps, while the other has a relatively smaller bandgap employing that their respective conductivity lies between the characteristics of a conductor and an insulator. Thus, conduction bands take a different form in the case of a semiconductor which is not the same as that of a metallic solid.