There are many types of Diode.According to the use of the semiconductor material, diode can be divided into the germanium diode (Ge tube) and silicon diodes (Si tube).According to its different uses, can be divided into the detector diodes, rectifier diodes, zener diodes, switching diodes and so on.According to the structure of the tube core can be divided into point contact diode, surface contact diode and planar diode.
The point contact diode with a very thin metal wire is pressed against the smooth surface of the semiconductor wafer, and pass to the pulse current, so that the contact wire at one end of the wafer firmly sintered together, forming a "PN "junction.
Due to point contact, only allowing through a smaller current (no more than tens of mA), suitable for small high-frequency current circuit, such as a radio detector.
The"PN junction area is larger in the surface contact type diode, allowed to pass through a larger current (several amps to tens An), mainly used for converting an alternating current into a DC rectifier circuit.
Plane diode is a special silicon diode, it can not only through a large current, and the performance is stable and reliable, mostly used in switching, pulse and high-frequency circuits.
The working principle of the diode:
Crystal diode as by p- type semiconductor and n-type semiconductor form of p-n junction, and the space-charge layer is formed in its both sides of the interface, and has a self farm. When the applied voltage is not present,Because of p-n junction on both sides of carrier concentration difference cause the diffusion current and self-built field cause the drift current equal and in electric balance state.
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