Difference between Conductor Semiconductor and Insulator

CHARACTERISTICS	CONDUCTOR	SEMI-CONDUCTOR	INSULATOR
Conductivity	High	Moderate	Low
Resistivity	Low	Moderate	Very High
Forbidden gap	No forbidden gap	Small forbidden gap	Large forbidden gap
Temperature coefficient	Positive	Negative	Negative
Conduction	Large number of electrons for conduction	Very small number of electrons for conduction	Moderate number of electrons for conduction
Conductivity value	Very high 10-7mho/m10-7mho/m	Between those of conductors and insulators i.e. 10-7mho/m10-7mho/mto 10-13mho/m10-13mho/m	Negligible like 10-13mho/m10-13mho/m
Resistivity value	Negligible; less than 10-5 Ω-m10-5 Ω-m	Between those of conductors and insulators i.e. 10-5 Ω-m10-5 Ω-m to 105 Ω-m105 Ω-m	Very high; more than 105 Ω-m105 Ω-m
Current flow	Due to free electrons	Due to holes and free electrons	Due to negligible free electrons
Number of current carriers at normal temperature	Very high	Low	Negligible
Band overlap	Both conduction and valence bands are overlapped.	Both bands are separated by an energy gap of 1.1eV	Both bands are separated by an energy gap of 6eV to 10eV
0 Kelvin Behavior	Acts like a superconductor	Acts like an insulator	Acts like an insulator
Formation	Formed by mettalic bonding	Formed by covalent bonding	Formed by ionic bonding
Valence Electrons	One valence electron in outermost shell	Four valence electron in outermost shell	Eight valence electron in outermost shell
Examples	Copper, mercury, aluminum, silver	Germanium, Silicon	Wood, Rubber, Mica, Paper

Difference between Conductors, Semiconductors, and Insulators on the Basis of Energy Bands

Conductors

In conductive materials, no band gaps exist so electrons move easily using a continuous, partly full conduction band.

Semiconductors

In semiconductor materials, the band gap between the conduction band and valence band is smaller and at normal temperature (room temperature), there is enough energy accessible to displace a few electrons from the valence band into the conduction band.
As temperature increases, the conductivity of a semiconductor material increases.

Insulator

In insulators, there is a large band gap between the conduction and valence band. The valence band remains full since no movement of electrons occurs and as a result, the conduction band remains empty as well.