Schottky Diode – Features & Applications

Dec 11, 2023

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Schottky diode is fabricated as a metal-to-N junction rather than a P-N semiconductor junction. Also referred to as hot-carrier diodes, Schottky diodes are characterized by fast switching times (low reverse-recovery time), low forward voltage drop (normally 0.25 to 0.4 volts for a metal-silicon junction), and low junction capacitance.

Fig: Schottky diode schematic symbol

The forward voltage drop (V_F), reverse-recovery time (t_rr) and junction capacitance (C_J) of Schottky diodes are closer to ideal than the average ‘rectifying’ diode. This makes them well suited for high-frequency application. However, Schottky diodes typically have lower forward current (I_F) and reverse voltage (V_RRM and V_DC) ratings than rectifying diodes and as a result they are unsuitable for applications involving significant amounts of power.

The technology based on Schottky diode is utilized widely in high-speed computer circuits, where the fast switching time equates to high speed capability, and the low forward voltage drop equates to less power dissipation when conducting.

Schottky diodes are used in low voltage switching regulator power supplies operating at 100’s of kHz where conventional silicon diodes cannot be used as rectifiers because of their slow switching speed. When the signal applied to a diode changes from forward to reverse bias, conduction continues for a short time, while carriers are being swept out of the depletion region. Conduction only ceases after this tr reverse recovery time has expired. Schottky diodes have a shorter reverse recovery time.

Another problem with the conventional silicon diodes is the 0.7 V forward voltage which causes poor efficiency in low voltage supplies. This might not be a problem in, for instance, a 10 V supply. In a 1 V supply the 0.7 V drop is a significant portion of the output. A remedy to this problem is to use Schottky power diode which has a lower forward voltage drop.

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