How to distinguish Schottky diodes from ordinary diodes?

Similarities: Schottky diodes share characteristics with ordinary PN junction diodes-forward conduction, reverse cutoff

difference:

High-frequency characteristics: In terms of the form of movement of carriers, when the PN junction is forward conducting, the holes injected from the P area to the N area or the electrons injected from the N area to the P area are all minority carriers, and they must first form a certain amount. The accumulation of, and then the formation of electric current under the diffusion movement. This charge storage effect seriously affects the high-frequency characteristics of the PN junction, and the forward current of the SBD is mainly formed by the majority of carriers in the semiconductor entering the metal. It is a multi-child device and does not need to be accumulated. So SBD has better high frequency characteristics than PN junction diode. Therefore, Schottky diodes are suitable for high-frequency rectification in low-voltage and high-current output situations, detection and mixing at high frequencies, and clamping in high-speed logic circuits. The PN junction fast recovery diode is mainly used as a rectifier element in the inverter power supply.

Forward conduction voltage VF: SBD has a low forward conduction voltage, generally about 0.3V; while the forward conduction voltage of PN junction silicon diode is about 0.7V

Reverse leakage current IR: The reverse characteristic SBD is inferior to the PN junction diode. SBD is more prone to thermal breakdown than PN junction diodes, and the reverse leakage current is larger than that of PN junction diodes.

Reverse recovery time trr: The recovery time of SBD is shorter than that of PN junction diode, and the reverse recovery time of SBD is 50 nS to 2 nS. The reverse recovery time of PN junction diode is: fast recovery diode less than 0.2uS; soft recovery Diode is less than 0.5 uS; ordinary rectifier diode is less than 100uS

Reverse withstand voltage: The reverse withstand voltage of PN junction diode is higher than that of SBD diode, and the reverse withstand voltage of fast recovery diode with shorter reverse recovery time is mostly below 1200V; while the commonly used model SBD is below 200V, which changes rapidly with technology , New products of SBD over 1kV have also come out. New materials break the situation of SBD's low withstand voltage.

Conduction loss and switching loss: SBD has no carrier storage effect, and the switching speed is very fast. The series resistance of the structure of metal and semiconductor contact is very small, so its switching loss is very small.

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