What is the reason for the large forward voltage drop of the fast recovery diode?

What is the reason for the large forward voltage drop of the fast recovery diode?

When testing the fast recovery diode circuit, the fast recovery diode is abnormal, and the PN junction will cause the forward voltage drop of the fast recovery diode to be large.

The internal structure of the fast recovery diode is different from that of ordinary diodes, and it adds base region I in the middle of P-type and N-type silicon materials to form P-I-N silicon wafers. Due to the thin base area, the reverse recovery charge is small, which not only greatly reduces the TRR value, but also reduces the transient forward voltage drop, so that the diode can withstand high reverse operating voltages.

fast recovery diode typically have a reverse recovery time of several hundred nanoseconds, a forward voltage drop of about 0.6V, a forward current of a few amperes to several thousand amperes, and a reverse peak voltage of several hundred to several thousand volts. The reverse recovery charge of the ultrafast recovery diode is further reduced, allowing its trr to be as low as tens of nanoseconds. If the forward voltage drop of the measured fast recovery diode is abnormally large, it may be that the diode with PN structure has been bought.