Basic knowledge and characteristics of rectifier diodes

Rectifier diode is a semiconductor device used to convert alternating current into direct current. Usually it contains a PN junction with two terminals, anode and cathode. The carriers in the P area are holes, and the carriers in the N area are electrons, forming a certain barrier between the P area and the N interval. When a voltage that makes the P area positive relative to the N area is applied, the potential barrier is lowered, and stored carriers are generated near both sides of the barrier, which can pass large currents and have a low voltage drop (typical value 0.7V), which is called forward conduction Pass state. If the opposite voltage is applied, the potential barrier is increased, which can withstand high reverse voltage and flow a small reverse current (called reverse leakage current), which is called reverse blocking state. Rectifier diodes have obvious unidirectional conductivity.

The rectifier diode can be made of materials such as semiconductor germanium or silicon. The silicon rectifier diode has high breakdown voltage, low reverse leakage current and good high temperature performance. Generally, high-voltage and high-power rectifier diodes are made of high-purity monocrystalline silicon (it is easy to reverse breakdown when there is more doping). This kind of device has a large junction area and can pass a large current (up to thousands of amperes), but the operating frequency is not high, generally below tens of kilohertz. Rectifier diodes are mainly used in various low-frequency half-wave rectifier circuits. If full-wave rectification is required, they must be connected as a rectifier bridge. The rectifier diode uses the unidirectional conductivity of the PN junction to convert alternating current into pulsating direct current. Rectifier diodes flow relatively large currents, and most of them are diodes packaged with surface contact materials. The shape of the rectifier diode is shown in Figure 1. In addition, the parameters of the rectifier diode include the maximum rectified current, which refers to the maximum current allowed by the rectifier diode for long-term operation. It is the main parameter of the rectifier diode and the main basis for the option of the rectifier diode.