The main characteristics and principles of Schottky diodes

The main characteristics and principles of Schottky diodes

Schottky diodes are a type of semiconductor device made of precious metals such as gold, silver, aluminum, platinum, etc A serves as the positive electrode, and N-type semiconductor B serves as the negative electrode, utilizing the rectification characteristics of the potential barrier formed on the contact surface of the two. Schottky diodes have a lower reverse breakdown voltage: SBD has a relatively lower reverse breakdown voltage because its reverse barrier is thin and its surface is prone to breakdown. Because SBD is more prone to thermal breakdown than PN junction diodes, the reverse leakage current is greater than PN junction diodes.

The forward voltage of the Schottky barrier diode decreases: because the height of the Schottky barrier is lower than that of the PN junction barrier, its forward conduction mosfet and forward voltage drop are lower than those of the PN junction diode (about 0.2V lower). Schottky diodes have a high operating frequency: due to the small storage effect of minority carriers in Schottky diodes, their frequency response is only limited by the RC time constant, making them ideal devices for high-frequency fast switching. Its operating frequency can reach 100 GHz.

Schottky diodes have fast reverse recovery time: because SBD is a majority carrier conductive device, there are no minority carrier lifetime and reverse recovery issues. The reverse recovery time of SBD is only the charge and discharge time of Schottky barrier capacitor, which is completely different from the reverse recovery time of PN junction diode. Due to the very small reverse recovery charge of SBD, the switching speed is very fast, and the switching loss is very small, making it particularly suitable for high-frequency applications.

Schottky diode is mainly used as high frequency, low voltage, high current rectifier diode, Flyback diode and protection diode, as well as rectifier diode and small signal detection diode in Microwave transmission circuit. Commonly used for secondary power rectification and high-frequency power rectification of color televisions.

The basic principle of Schottky diodes is that at the contact surface between metal and N-type silicon wafers, the current is controlled by a potential barrier formed by the contact between metal and semiconductor. The rectification principle of Schottky junction and PN junction is fundamentally different. Its withstand voltage is only around 40V, mostly not higher than 60V, which limits its application range. Its characteristic is that the switching speed is very fast, and the reverse recovery time is particularly short. Therefore, switching diodes and low-voltage high current rectifier diodes can be manufactured.