The internal structure of the quick recovery diode is different from that of the ordinary PN junction diode. It belongs to the PIN junction diode, that is, the base region I is added between the P-type silicon material and the N-type silicon material to form the PIN silicon wafer. Because the base region is very thin, the reverse recovery charge is very small, so the reverse recovery time of the fast recovery diode is short, the forward voltage drop is low, and the reverse breakdown voltage (withstand voltage value) is high.

The internal structure of the fast recovery diode is different from that of the ordinary diode. It is composed of P-I-N silicon wafer by adding the base region I in the middle of the P-type and N-type silicon material. Because the base area is very thin and the reverse recovery charge is very small, not only the trr value is greatly reduced, but also the transient forward voltage drop is reduced, so that the tube can withstand very high reverse operating voltage. The reverse recovery time of the fast recovery diode is generally a few hundred nanoseconds, the forward voltage drop is about 0.6V, the forward current is several amps to several thousand amps, and the reverse peak voltage can be several hundred to several thousand volts. The reverse recovery charge of the ultrafast recovery diode is further reduced, so that its trr can be as low as tens of nanoseconds. The fast recovery and ultra-fast recovery diodes below 20A are mostly in TO-220 package. From the internal structure, can be divided into single tube, tube (also called double tube) two. The inside of the tube contains two quick recovery diodes, and according to the different connection methods of the two diodes, there are a common Yin to the tube, a common Yang to the tube. Figure 2(a) shows the appearance and internal structure of C20-04 type quick recovery diode (single tube). Figure (b) and Figure (c) respectively show the appearance and structure of C92-02 (common negative pair) and MUR1680A (common positive pair) ultrafine recovery diodes. They are packaged in TO-220 plastic, tens of AmPs fast recovery diodes are generally packaged in TO-3P metal shell. Larger capacity (several hundred amps to several thousand amPs) pipe is used in bolt type or plate type package form.