Forward bias

Forward bias is a voltage polarity across a semiconductor junction that lowers its potential barrier and promotes current by enabling charge carriers to cross the junction.

Semiconductor p–n junction: A boundary between p-type and n-type semiconductor regions, where carrier diffusion creates a depletion region and potential barrier. Forward bias acts across this junction and reduces its built-in barrier.
P-type semiconductor: A semiconductor doped to make holes its majority mobile charge carriers. Its holes are driven toward the junction by the forward-bias polarity.
Diode: A two-terminal electronic component that conducts asymmetrically, allowing substantially more current in one direction than the other. Forward bias is the diode’s principal conducting condition.
Reverse bias: A voltage polarity across a semiconductor junction that raises its potential barrier and suppresses carrier flow. It applies the opposite junction polarity and normally reduces current.
Depletion region: A semiconductor junction region depleted of mobile carriers and containing fixed ionized dopants. The applied polarity narrows this region as the junction conducts.
N-type semiconductor: A semiconductor doped to make electrons its majority mobile charge carriers. Its electrons are driven toward the junction under forward bias.
Light-emitting diode: A semiconductor diode that emits light when electrons and holes recombine under forward current. Its forward-biased junction converts carrier recombination into emitted photons.
Avalanche breakdown: A high-field process in which carriers create additional electron–hole pairs by impact ionization. It can produce large current under reverse bias, unlike ordinary forward conduction.
Built-in potential: The equilibrium voltage across a semiconductor junction created by charge separation. Forward voltage opposes this junction potential, lowering the barrier to carrier diffusion.
Doping (semiconductor): The deliberate addition of impurities to a semiconductor to change its electrical properties. Doping creates the p-type and n-type regions that give a junction its polarity.

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