Insulators are used daily by all of us, 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.
Key Takeaways
- Insulators are materials that do not conduct electricity well and have high resistivity, while semiconductors have moderate resistivity and conductivity.
- Semiconductors can conduct electricity under certain conditions and are used in electronic devices, while insulators are used to prevent electricity from flowing.
- The conductivity of semiconductors can be increased by adding impurities through doping, while insulators cannot be doped to increase their conductivity.
Insulator vs Semiconductor
A massive gap between the valance band and conduction band in the insulator prevents free electrons from conducting electricity. On the other side, semiconductors have less bandgap than insulators, which high energetic electrons can overcome.
Insulators are poor conductors of heat and electricity. Their resistance is very high, so 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 difference in conduction.
The semiconductors can be pure such as germanium and silicon, or compounds, such as gallium arsenide or cadmium selenide.
Comparison Table
| Parameters of comparison | Insulator | Semiconductor |
|---|---|---|
| Conductivity | < 10 -13 mho/m | Between 10 -7 to 10 -13 mho/m |
| Majority charge carriers | No conduction due to the absence of carriers | Movement of electrons and holes |
| No. of valence electrons | Their valence shell is complete, i.e. 8 electrons | They have four valence electrons in the outermost shell |
| Bandgap | There is a huge bandgap of 6eV -10eV | There is a bandgap of 1.1eV |
| Valence band | Filled | Partially empty |
| Conduction band | Empty | Partially filled |
| Absolute zero | Resistance increases | Turn into an insulator |
| Resistivity | High | Moderate |
| Example | Rubber, plastic, paper, etc | Silicon, germanium, gallium arsenide |
| Applications | Home appliances, coating of cable wires, etc | Integrated 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, a huge bandgap of 6eV to 10eV does not allow electrons to jump from the valence band to the conduction band. They have a filled valence band and an empty conduction band.
They have very high resistance because of which no current can pass through them. On 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. A 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 conductance level can be altered by adding several impurities to the semiconductor crystal.
There are pure semiconductor crystals like silicon or germanium and compound semiconductors like gallium arsenide or cadmium selenide.
There are mainly two types of a semiconductor having huge applications in modern electronics industries. They are intrinsic semiconductors (Si and Ge) and extrinsic semiconductors (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, holes and electrons, that conduct electricity. 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.
They lose their conductance property at zero temperature and turn into insulators. They are very compact, have a long life application, and have low cost, which makes them very in demand in modern technologies.
Semiconductors have a huge application in making diodes and transistors, MOSFET, etc.
Main Differences Between Insulators and Semiconductors
- 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.
- They have a different energy bandgap; that is, for semiconductors, it is 1.2eV, and for insulators, it is 10eV.
- Insulators do not have any carriers in them, so there is no conductivity in them, and on the other hand, semiconductors have electrons and holes to conduct.
- At absolute zero temperature, the resistance to the insulator increases, whereas the semiconductor completely loses its conductance and behaves as an insulator
- The insulators have only covalent bonding, whereas the semiconductors have both ionic and covalent bonding.
- The insulators have a complete valence shell, and semiconductors have a partially filled valence shell with 4 electrons.
- Insulators have a very high resistance which does not allow electricity or heat to flow through them. Still, semiconductors have a moderate resistance, allowing the flow to the current but sometimes blocking it.
Reference
- https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.9b04187?casa_token=Udhvcpd5v4QAAAAA:JLS2H_D2xAnvWgO3b373dzQ-8TOgwXYYyKu5bszsg0-5cJpD0ZAw4JzzkdJFcCTr8JNYJym4qmUROCFQ
- https://journals.aps.org/prb/abstract/10.1103/PhysRevB.27.7509
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