Biasing, Forward-biased, Reversed-biased, Zero-biased in diode, p-n junction

Biasing
- applying voltage to a circuit to allow or prevent current flow.


Zero bias
- equilibrium condition in a diode or pn junction
- no external voltage applied in a p-n junction
- potential difference (built-in potential) exists across the junction


Reverse bias
- cathode voltage higher than anode voltage
- barrier voltage increases
- depletion zone width increases
- depletion region widens
- junction barrier widens
- resistance becomes greater
- prevents flow of charge carriers
- no current will flow (or minimal current flows)
- acts like an insulator


Forward bias
- barrier voltage decreases
- depletion width is reduced
- barrier potential lowered
- electrical resistance reduced
- allows current flow (conduction mode)
- current flows in the same direction on both sides of diode
- behaves like a conductor


P–N Junction Diode
- electric charges flow in one direction only
- like a mechanical check valve in piping (allowing fluid to flow in one direction only)