Ultrafast recovery diode (fred) is a kind of semiconductor diode with good switching characteristics and ultra-short reverse recovery time, which is commonly used for the switching device of high frequency inverter as a continuous current, absorption, clamping, isolation, output and input rectifier, so that the function of the switching device can be fully played. Ultrafast recovery diode is an important and indispensable device for the development of high-frequency (above 20khz) and solid-state high-frequency equipment.