The working principle and type of diode

The working principle of the diode:

The crystal diode is a p-n junction formed of a p-type semiconductor and an n-type semiconductor, and a space charge layer is formed on both sides of the interface, and a self-built electric field is built. When there is no applied voltage, the diffusion current caused by the difference in carrier concentration on both sides of the p-n junction is equal to the drift current caused by the self-built electric field, and is in an electrical equilibrium state. When the outside is biased by the forward voltage, the mutual suppression of the external electric field and the self-built electric field causes the diffusion current of the carrier to increase to cause a forward current. When the outside has a reverse voltage bias, the external electric field and the self-built electric field are further strengthened to form a reverse saturation current I0 that is independent of the reverse bias voltage value within a certain reverse voltage range. When the applied reverse voltage is high enough To the extent that the electric field strength in the space charge layer of the pn junction reaches a critical value, a multiplication process of carriers is generated, a large number of electron hole pairs are generated, and a large reverse breakdown current is generated, which is called a diode breakdown phenomenon. There are also some typical bridge stacks and rectifier bridges that require attention and attention.

Type of diode:

There are many types of diodes, which can be classified into germanium diodes (Ge tubes) and silicon diodes (Si tubes) depending on the semiconductor material used. According to its different uses, it can be divided into detection diodes, rectifier diodes, Zener diodes, switching diodes, etc. According to the die structure, it can be divided into point contact diodes, surface contact diodes and planar diodes. The point contact diode is pressed on the surface of a clean semiconductor wafer with a very thin wire, and a pulse current is applied to firmly seal one end of the contact wire with the wafer to form a "PN junction". Due to the point contact, only a small current (not more than tens of milliamps) is allowed, which is suitable for high frequency and small current circuits, such as radio detection. The "PN junction" area of the surface contact diode is large, allowing a large current (a few amps to several tens of amps) to be used, mainly for converting the alternating current into a "rectifying" circuit of direct current. The planar diode is a special type of silicon diode. It can not only pass large current, but also has stable and reliable performance. It is mostly used in switching, pulse and high frequency circuits. Some of the better diode manufacturers of Guangdong diodes and chip diodes. They are very focused on their performance and quality.