Distinguish between 'intrinsic' and 'extrinsic' semiconductors.
Intrinsic Semiconductor -- It is pure, natural semiconductor, such as
pure Ge and pure Si .
- In it the concentrations of electrons and
holes are equal.
- Its electrical conductivity is very low.
- Its conductivity cannot controlled.
- Its conductivity increases exponentially
with temperature
Extrinsic Semiconductor-
- It is prepared by adding a small quantity of
impurity to a pure semiconductor, such as n-and p-type
semiconductors.
- In it the two concentrations are unequal. There is
an excess of electrons in n-type semiconductors
and an excess of holes in p-type semiconductors.
- Its electrical conductivity is significantly high.
- Its conductivity can be controlled by adjusting the
quantity of the impurity added.
- Its conductivity also increases with temperature,
but not exponentially.