Operating Principle Of Diode

The main principle of the diode is to make use of the unidirectional conductivity of the PN junction, and add leads and packages to the PN junction to form a diode.

The crystal diode is a PN junction formed by P type semiconductor and N type semiconductor. A space charge layer is formed on both sides of its interface, and a self built electric field is built. When there is no applied voltage, the diffusion current caused by the carrier concentration difference on both sides of the PN junction is equal to the drift current caused by the self built electric field and is in electric balance.

When there is a positive voltage bias outside, the mutual suppression of the external electric field and the self built electric field makes the carrier diffusion current increase and causes a positive current. When there is reverse voltage bias outside, the external electric field and self built electric field are further strengthened, forming a reverse saturation current independent of the reverse bias voltage within a certain reverse voltage range.