Conductors, semiconductors and insulators

The crucial difference between conductor, semiconductor, and insulator depends on their level of conductivity . Conductors are basically the materials that allow easy flow of electric current, therefore, they exhibit high conductivity, semiconductors are the materials that possess moderate conductivity. And on the contrary, insulators are the materials that prevent the flow of charge through them, thus exhibiting low conductivity.

This is the main factor that distinguishes all three. However, there are some other differences between conductor, semiconductor, and insulator that we will discuss later. If you have any questions that arise while reading our article, do not hesitate to leave it detailed in a comment below, we will help you solve it as soon as possible.

Energy gapDoes not existSmall (1 eV)Large (> 5 eV)
ConductivityAlta (10-7 mho / m)Mediana (10-7 and 10-13 mho / m)Very low (10-3 mho / m), almost negligible.
Current flowDue to the movement of free electrons.Due to the movement of electrons and holes.Almost negligible but only due to free electrons.
Temperature coefficient of resistancePositiveNegativeNegative
Charge carriers in conduction bandCompletely fullPartially fullCompletely vacant
Valencia band charge carriersAlmost vacantPartially fullCompletely full
ExamplesCopper, aluminum, graphite, etc.Silicon, germanium, arsenic, etc.Paper, rubber, glass, plastic, etc.
ApplicationsLead wires, transformers, electric cables, etc.Diodes, transistors, optocouplers, etc.Sports equipment, appliances, etc.

Definition of conductor

The drivers are substances that allow easy flow of electricity through them . More specifically, we can say that it allows the easy flow of electrons from one atom to another when a suitable electric field is applied to it. These are the materials that possess the highest conductivity among the three. Now, the question that catches our attention is what is conductivity? It is the property of a material by which it allows a large amount of current to flow through it.

Mainly the movement of electrons within the material is responsible for its conduction . And these electrons show motion when a certain voltage is applied to them. This voltage applies a force to the electrons because they easily begin to move from the valence band to the conduction band. Therefore, these are good conductors of electricity .

Let’s take a look at the energy level diagram of the conductors:

The two bands, that is, the valence band and the conduction band, overlap each other. Therefore, when a certain voltage is applied to such materials, electrons easily move from the valence band to the conduction band due to the influence of the electric field. This movement of the charge carriers generates a large electrical current through the device .

Definition of semiconductor

The semiconductors are materials that have a property of lower electrical conductivity than the conductors . Charge carriers in the case of semiconductors are electrons and holes. When the temperature is absolute zero, then no movement of charge carriers occurs in the case of semiconductors. In such a case, it behaves as insulators.

But for a considerable flow of charge carriers to take place, they must be provided with a certain potential that can excite the electrons to another energy level . In this way, it generates electric current.

Let’s take a look at the diagram of the energy level of semiconductors:

As we can see in the figure above, the energy band gap is present between the valence band and the conduction band . Although this energy difference was not present in the previously discussed case of conductors. In the case of semiconductors, the two bands do not overlap , therefore there is a small difference in energy between them. So the electrons in the valence band cannot be automatically excited to move to the conduction band. But, by applying a certain voltage, the electrons in the valence band gain enough energy and jump to the conduction band.

Definition of insulator

The insulators are materials that are not good conductors of electrical charges . As in the case of insulators, current cannot flow easily through them. The gap in the energy band is so high in the case of insulators that even the applied potential does not excite electrons from the valence band to the conduction band. But since they have a negative coefficient of resistance to temperature, therefore, with increasing temperature, the resistance they offer decreases.

Let’s take a look at the energy level diagram of an insulator:

Here, as we can see, there is a large gap between the valence band and the conduction band . This large band gap does not allow electrons to jump within the conduction band. Therefore, current flow is not possible.

The band gap in the case of insulator is higher compared to conductors and insulators. However, there is a case of insulating materials breakdown where when an extremely high temperature is provided or supplied , then it causes the electrons to overcome the large energy difference, thus moving into the conduction band.

Key differences between conductor, semiconductor and insulator

  • The factor that generates a key difference between the conductor, the semiconductor and the insulator is that the energy gap between the conduction band and the valence band does not exist since the two bands overlap in the case of the conductor. In contrast, the energy gap between the valence and the conduction band is small in the case of semiconductors. And finally, there is a great energy difference between the two bands in the case of insulators.
  • As conductors allow a large flow of electrical current, it has a low resistivity compared to semiconductors whose resistivity is moderate . On the other hand, the insulator has the highest resistivity of all .
  • Conductors are highly conductive in nature, while semiconductors are moderately conductive. On the contrary, the conductivity of the insulators is almost negligible.
  • Conductors are materials that exhibit a positive temperature coefficient of resistance , as resistance increases with increasing temperature. While semiconductors and insulators have a negative temperature resistance coefficient as their resistivity decreases with increasing temperature.
  • In the case of conductors, the conduction band is completely full, in semiconductors, it is partially full, while in isolators the conduction band is totally empty.
  • The valence band in conductors is almost empty, in semiconductors, it is partially full as some electrons are present in the conduction band due to the small band gap. However, the valence band is completely filled in the case of insulators because there is a large band gap between the valence and the conduction band.
  • Common conductors are copper, aluminum, graphite, iron, etc. Silicon and germanium are examples of semiconductors. While common insulators are paper, rubber, glass, plastic, etc .


So from the above discussion, we can conclude that the movement of electrons from the valence band to the conduction band is responsible for the current flow . The presence of electrons in the conduction band decides the level of conduction of the material. Therefore, the conductivity level of semiconductors is somewhere between conductors and insulators.

Ready, so far we have arrived with our article referring to conductors, semiconductors and electrical insulators . If you have any problem that has arisen while reading it, feel free to comment below. We will try to help you as soon as possible and remove your doubts. In turn, we would appreciate if you share the article on your favorite social networks, such as Facebook, Twitter, etc. so that your followers can visit us and find out just like you did,

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