Semi-conductor

Semi-conductor

• A semiconductor material has an electrical conductivity value falling between that of a conductor, such as metallic copper, and an insulator, such as glass. 
• Its resistivity falls as its temperature rises; metals behave the opposite. 
• Its conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. 
• When two differently-doped regions exist in the same crystal, a semiconductor junction is created.
• c.f., p-n junction
• a boundary or interface between two types of semiconductor materials, p-type and n-type, inside a single crystal of semiconductor. 
• The "p" (positive) side contains an excess of holes, while the "n" (negative) side contains an excess of electrons in the outer shells of the electrically neutral atoms there. 
• This allows electrical current to pass through the junction only in one direction.
• c.f., holes
• the lack of an electron
• The p-n junction is created by doping
• c.f., doping
• the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties
• c.f., charge carrier
• a particle or quasi-particle that is free to move, carrying an electric charge
• The behavior of charge carriers, which include electrons, ions and electron holes, at these junctions is the basis of diodes, transistors and all modern electronics.

Difference of semiconductors and conductors

• Conductors
• hard to control although it conducts well
• Semiconductors
• easy to change its properties by applying an artificial manipulation such as adding impurities
• Different manipulations can lead to different things a semiconductor can do