Difference between Conductor Semiconductor and Insulator

This article covers the key differences between Conductor, Semiconductor, and Insulator on the basis of Conductivity, Resistivity, Forbidden Gap, Conduction, Band Structure, Current Flow, Band Overlap, 0 Kelvin Behavior, and Examples. The following table covers the key Differences between the Conductor, Semiconductor, and Insulator.

Difference between Conductor Semiconductor and Insulator

ResistivityLowModerateVery High
Forbidden gapNo forbidden gapSmall forbidden gapLarge forbidden gap
Temperature coefficientPositiveNegativeNegative
ConductionLarge number of electrons for conductionVery small number of electrons for conductionModerate number of electrons for conduction
Conductivity valueVery high $\text{1}{{\text{0}}^{\text{-7}}}\text{mho/m}$Between those of conductors and insulators i.e. $\text{1}{{\text{0}}^{\text{-7}}}\text{mho/m}$ to $\text{1}{{\text{0}}^{\text{-13}}}\text{mho/m}$Negligible like $\text{1}{{\text{0}}^{\text{-13}}}\text{mho/m}$
Resistivity valueNegligible; less than $\text{1}{{\text{0}}^{\text{-5}}}\text{ }\Omega \text{-m}$Between those of conductors and insulators i.e. $\text{1}{{\text{0}}^{\text{-5}}}\text{ }\Omega \text{-m}$ to $\text{1}{{\text{0}}^{\text{5}}}\text{ }\Omega \text{-m}$Very high; more than $\text{1}{{\text{0}}^{\text{5}}}\text{ }\Omega \text{-m}$
Current flowDue to free electronsDue to holes and free electronsDue to negligible free electrons
Number of current carriers at normal temperatureVery highLowNegligible
Band overlapBoth conduction and valence bands are overlapped.Both bands are separated by an energy gap of 1.1eVBoth bands are separated by an energy gap of 6eV to 10eV
0 Kelvin BehaviorActs like a superconductorActs like an insulatorActs like an insulator
FormationFormed by mettalic bondingFormed by covalent bondingFormed by ionic bonding
Valence ElectronsOne valence electron in outermost shellFour valence electron in outermost shellEight valence electron in outermost shell
ExamplesCopper, mercury, aluminum, silverGermanium, SiliconWood, Rubber, Mica, Paper

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


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

Conductor Energy Band


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.

Semiconductor Energy Band


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.

Insulator Energy Band