Semiconductors

Description:

Conductor

A material that allows electricity to pass through it is known as conductor. Charges are allowed to move freely in the conductor.

E.g.: Usually metals are conductors.

Insulator

A material which does not allow electricity to pass through it is known as insulator. Charges are not allowed to move in insulator.

E.g.: Plastic, wood are insulators.

Semiconductors

A material that can behave as a conductor as well as an insulator is known as semiconductor.

E.g.: germanium, silicon etc.

Conductivity

The measurement of charges which are allowed to flow in a material is known as conductivity of the material.

Resistivity

The measurement of the resisting power i.e. restriction to the flow of charge in the material, is called as resistivity.

conductivity = 1/resistivity

Observations

• Conductors have high conductivity and very low resistivity.
• Insulator have low conductivity and high resistivity.
• Semiconductors have conductivity and resistivity in between the conductor and insulator.

Types of Semiconductors

• Elemental Semiconductors: Silicon (Si), Germanium (Ge)

• Compound Semiconductors: There can be three types of Compound semiconductors –

  • Inorganic semiconductors: Cadmium sulphide (Cd S), Gallium arsenide (Ga As), Cadmium selenide (Cd Se), Indium phosphide (In P).

  • Organic semiconductors: Anthracene, Phthalocyanine.

  • Organic Polymers: Polypyrrole, Polyaniline, Polythiophene.