Question

write the two points of differences between intrinsic and extrinsic semiconductors

Answer 1

Intrinsic semiconductor are puresemiconductor .their conductivity is poor and as such they do not find much application. Extrinsic semiconductor are semiconductorswhen a trivalent or pentavalent impurity is added to a puresemiconductor , extrinsic semiconductor is obtained.

Answer 2

INTRINSIC

It is pure semi-conducting material and no impurity atoms are added to it.

 

Examples: crystalline forms of pure silicon and germanium.

 

The number of free electrons in the conduction band and the no. of holes in valence band is exactly equal and very small indeed.

Its electrical conductivity is low.

Its electrical conductivity is a function of temperature alone.

EXTRINSIC

It is prepared by doping a small quantity of impurity atoms to the pure semi-conducting material.

Examples: silicon “Si” and germanium “Ge” crystals with impurity atoms  of As, Sb, P etc. or In B, Aℓ etc.

The number of free electrons and holes is never equal. There is excess of electrons in n-type semi-conductors and excess of holes in p-type semi-conductors.

Its electrical conductivity is high.

Its electrical conductivity depends upon the temperature as well as on the quantity of impurity atoms doped the structure.