Difference Between Insulator and Semiconductor (With Table)

Insulators are used every day by all of us starting from panhandles to underground pipe coating. On the other hand, semiconductor materials are mainly used in electronic devices and have great use in our electronics industries.

Insulator vs Semiconductor

The difference between insulators and semiconductors is that the rate of conductivity differs in them. There is a huge gap between the valance band and conduction band in the insulator which prevents free electrons to conduct electricity. On the other side, semiconductors have a less bandgap compared to insulators which can be overcome by high energetic electrons.

Insulators are poor conductors of heat and electricity. Their resistance is very high due to which electricity can’t pass through them. They are mainly used in insulating conduction wires. They form a barrier between two conducting bodies to prevent short-circuiting and accidents. Some common insulating materials are paper, wood, rubber plastics, etc.

Semiconductors have a moderate conductivity level. Their resistance to electricity can be varied by adding impurities in it. This process is called doping. A small amount of added impurity can lead to a huge amount of difference in conduction. The semiconductors can be pure such as germanium and silicon or can be compounds such as gallium arsenide or cadmium selenide.

Comparison Table Between Insulator and Semiconductor

Parameters of comparison  InsulatorSemiconductor
Conductivity< 10 -13 mho/mBetween 10 -7 to 10 -13 mho/m
Majority charge carriersNo conduction due to the absence of carriersMovement of electrons and holes
No. of valence electronsTheir valence shell is complete i.e. 8 electronsThey have 4 valence electrons in the outermost shell
BandgapThere is a huge bandgap of 6eV -10eVThere is a bandgap of 1.1eV
Valence bandFilledPartially empty
Conduction bandEmptyPartially filled
Absolute zeroResistance increasesTurn into an insulator
ResistivityHighModerate
ExampleRubber, plastic, paper, etcSilicon, germanium, gallium arsenide
ApplicationsHome appliances, coating of cable wires, etcIntegrated circuits, diodes, resistors, etc

What is Insulator?

 A material that is a very poor conductor of heat or electricity is called an insulator. Its conductance level is very low. Conduction is the property of easy flow of current carries through them. Insulators have a complete valence band of 8 electrons in them. As a result, there is an absence of free carriers to conduct electricity.

According to band theory, there is a huge bandgap of 6eV to 10eV that does not allow electrons to jump from the valence band to the conduction band. They have a filled valence band and a empty conduction band. They have very high resistance because of which no current can pass through them. On the increasing temperature, the resistivity of an insulator decreases. Temperature leads to loosing of covalent bonds present in them and increases the number of carriers in them.

At absolute zero temperature, the resistance of the insulator increases. There are many types of insulators such as sound insulators, thermal insulators, and electrical insulators depending upon the field of the use of the material. Pin insulators are the first insulators used. Vacuum is also an insulator. This is due to the fact of absence of carriers there. Some examples of insulators are rubber, plastic, etc.

What is Semiconductor?

A material whose conductance level is intermediate between conductor and insulator is known as a semiconductor. The level of conductance can be altered by adding a small amount of impurities to the semiconductor crystal. There are pure semiconductor crystals like silicon or germanium as well as compound semiconductors such as gallium arsenide or cadmium selenide.

There are mainly two types of a semiconductor having huge applications in modern electronics industries. They are intrinsic semiconductor (Si and Ge) and extrinsic semiconductor (n-type and p-type). The n-type extrinsic semiconductor is formed by adding group III elements in pure Si or Ge. These impurities are called donors. The p-type extrinsic semiconductor is formed by adding group V elements in pure Si or Ge. These impurities are known as acceptors.

They have both types of carriers in them that are electricity is conducted both by holes and electrons. Their conductance is between 10-7 to 10-13 mho/m. They have a moderate energy band gap covered by electrons to move to the conduction band. Their valence band is partially filled with 4 electrons. They have a covalent type of bonding.

At absolute zero temperature, they lose their conductance property and completely turn into insulators. They are very compact, have a long life application, and low cost which makes them very demanded in modern technologies. The semiconductors are having a huge application in making diodes, transistors MOSFET, etc.

Main Differences Between Insulator and Semiconductor

  1. The key difference between insulators and semiconductors is their range of conductivity. The conductance of the insulator is 10-13 mho/m whereas semiconductors have conductance between 10-7 to 10-13 mho/m.
  2. They have a different energy bandgap, that is for semiconductors it is 1.2eV and for insulators, it is 10eV.
  3. Insulators do not have any carriers in them so there is no conductivity in them and on the other hand semiconductors have both electrons and holes to conduct.
  4. At absolute zero temperature, the resistance to the insulator increases whereas the semiconductor completely loses its conductance and behaves as an insulator
  5. The insulators have only covalent bonding whereas the semiconductors have both ionic and covalent bonding in them.
  6. The insulators have a complete valence shell and semiconductors have a partially filled valence shell with 4 electrons.
  7. Insulators have a very high resistance which does not allow electricity or heat to flow through them but semiconductors have a moderate resistance which allows the flow to current but sometimes blocks it.

Conclusion

Both insulators and semiconductors have a huge impact on our daily life. Their difference in properties makes them useful in different fields of life. Insulators are used to break the flow of heat, electricity, or sound from its normal flow in conduction. Semiconductors are low and compact and useful to make small circuit elements and also have a long working life.

Reference

  1. https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.9b04187?casa_token=Udhvcpd5v4QAAAAA:JLS2H_D2xAnvWgO3b373dzQ-8TOgwXYYyKu5bszsg0-5cJpD0ZAw4JzzkdJFcCTr8JNYJym4qmUROCFQ
  2. https://journals.aps.org/prb/abstract/10.1103/PhysRevB.27.7509

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