P–n junction

A boundary between p-type and n-type semiconductor regions where carrier diffusion creates a charge-depleted region and an internal electric field, producing rectifying behavior.

Depletion region: A semiconductor region depleted of mobile electrons and holes, containing fixed ionized dopants. It forms at the junction as electrons and holes diffuse across the boundary.
Semiconductor: A material whose electrical conductivity lies between that of a conductor and an insulator and can be controlled. The junction is formed within this class of materials.
Semiconductor diode: A two-terminal semiconductor device that conducts current more readily in one direction than the other. A single p–n junction is the basic structure of many semiconductor diodes.
Schottky barrier: An energy barrier formed at a metal–semiconductor contact. Unlike this junction, it joins a metal to a semiconductor rather than two doped regions.
Built-in potential: The electrostatic potential difference established across a semiconductor junction at equilibrium. The exposed dopant ions create this barrier against further carrier diffusion.
Doping (semiconductor): The deliberate addition of impurities to a semiconductor to change its carrier concentration. Different dopants create the p-type and n-type regions that meet at the boundary.
Light-emitting diode: A semiconductor diode that emits light when injected electrons and holes recombine. Its forward-biased junction drives the carrier recombination that produces light.
Ohmic contact: A metal–semiconductor contact designed to have low resistance and nearly linear current-voltage behavior. It provides electrical connection without the strong rectification characteristic of a p–n boundary.
Forward bias: A voltage polarity that lowers a junction’s potential barrier and increases its current. It reduces the barrier at this junction, allowing substantial carrier injection.
P-type semiconductor: A doped semiconductor in which holes are the majority mobile charge carriers. Its holes diffuse toward the n-type side when the regions are joined.

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