Semiconductors

Semiconductor

Material with a resistivity between that of a good conductor and a good insulator, and decreases with temperature

What happens in terms of charge carriers when a semiconductor is heated?

As temperature increases, charge carriers release many electrons from their atoms. This leads to an increase electron hole pairs, leading to a decrease in resistance.

Intrinsic conduction

Conduction in a pure semiconductor with an equal number of holes and electrons moving in the opposite direction

Extrinsic Conduction

Increased conduction in a doped semiconductor with an unequal number of holes and electrons.

Relationship between resistance and temperature in a semiconductor

Resistance decreases rapidly with temperature

Depletion layer

insulating region between p-type and n-type semiconductors where there are no free charge carriers

How does a depletion layer form

When electrons and holes combine to neutralise eachother

How to dope for p-type (more positive holes)

Boron

How to dope n-type (more free electrons)

Phosphorous