Conductor | Semi Conductor | Insulator | Difference between Conductor vs insulator vs semiconductor | Basic Electrical

 In this article, we will show the basic difference between conductor and insulator, and semiconductor. Because these 3 things will be needed to understand the band theory of solids, concept of conductor, insulator, and semiconductor. Let's start 

Characteristic or Parameters	Conductor	semiconductor	Insulator
Definition	A conductor is a material that allows the flow of charge when applied with a voltage.	A semiconductor is a material whose conductivity lies between conductor & insulator	An insulator is a material that does not allow the flow of current.
Temperature Dependence	The resistance of a conductor increases with an increase in temperature.	The resistance of a semiconductor decrease with temperature increases. it acts as an insulator at absolute zero	Insulator has very high resistance but it still decreases with temperature.
Conductivity	The conductors have very high conductivity (10-7 Ʊ /m), thus they can conduct electrical current easily.	They have intermediate conductivity ((10-7 Ʊ /m to 10-13 Ʊ /m), thus they can act as insulators & conductors at different conditions.	They have very low conductivity (10-13 Ʊ /m), thus they do not allow current flow.
Conduction	The conduction in conductors is due to the free electrons in metal bonding.	The conduction in semiconductors is due to the movement of electrons & holes.	There are no free electrons or holes thus, there is no conduction.
Band Gap	There is no or low energy gap between the conduction & valance band of a conductor. It does not need extra energy for the conduction state.	The bandgap of the semiconductor is greater than the conductor but smaller than an insulator i.e. 1 eV. Their electrons need a little energy for the conduction state.	The bandgap in the insulator is huge (+5 eV), which need an enormous amount of energy like lightning to push electrons into the conduction band
Resistivity	Low (10-5 Ω/m)	Normal (10-5Ω/m to 105 Ω/m)	Very High (105 Ω/m)
Coefficient of resistivity	It has a positive coefficient of resistivity i.e. its resistance increase with temperature	It has a negative coefficient of resistivity.	The coefficient of resistivity of an insulator is also negative but it has very huge resistance.
Absolute zero	Some special conductors turn into superconductors when supercooled down to absolute zero while others have a finite resistance	The semiconductors turn into insulators at absolute zero	The insulator’s resistance increase when cooled down to absolute zero.
Valence Electron in Outer Shell	1 Valence electron in an outer shell. Example: Gold, Copper, Silver, Aluminum, etc	4 Valence electron in an outer shell. Example: Silicon, Germanium, Selenium, Antimony, Gallium Arsenide (known as semi insulator), Boron, etc.	8 Valence electron in an outer shell. Example Rubber, Glass, Wood, Air, Mica, Plastic, Paper, etc
Application	The metals like iron & copper etc. that can conduct electricity are made into wires and cables for carrying electric current.	Semiconductors are used every day in electronic devices such as cellphone, computers, solar panels, etc as switches, amplifiers, etc.	The insulators are used for protection against high voltages & prevention of electrical short between cables in the circuit.