Basic knowledge and characteristics of rectifier diodes — SUNMATE

Basic knowledge and characteristics of rectifier diodes

A semiconductor device used to convert alternating current into direct current. Usually it contains a PN junction with two terminals, anode and cathode. The charge carriers in the P region are holes, while the charge carriers in the N region are electrons, forming certain potential barriers in the P and N regions. When a positive voltage is applied to the P region relative to the N region, the barrier decreases, and storage carriers are generated near both sides of the barrier, which can pass through a large current and have a low voltage drop (typical value is 0.7V), known as a forward conduction state. If the opposite voltage is applied, the barrier increases and can withstand a high reverse voltage, passing a small reverse current (called reverse leakage current), which is called a reverse blocking state. The rectifier diode has obvious unidirectional conductivity.

Rectifier diodes can be made of materials such as semiconductor germanium or silicon. Silicon rectifier diodes have high breakdown voltage, low reverse leakage current, and good high-temperature performance. Usually, high-voltage high-power rectifier diodes are made of high-purity single crystal silicon (which is prone to reverse breakdown when heavily doped). This type of device has a large junction area and can pass a large current (up to thousands of amperes), but its operating frequency is not high, usually below tens of kilohertz. Rectifier diodes are mainly used in various low-frequency half wave rectification circuits. To achieve full wave rectification, they need to be connected into a rectifier bridge for use. Rectifier diodes utilize the unidirectional conductivity of PN junctions to convert alternating current into pulsating direct current. The rectifier diode has a high current flow, and most diodes are packaged with surface contact materials. The appearance of the rectifier diode is shown in Figure 1. In addition to the parameters mentioned earlier, there is also the maximum rectifier current, which refers to the maximum current allowed to pass through the rectifier diode during long-term operation. It is the main parameter of the rectifier diode and the main basis for selecting the rectifier diode.