Schottky diodes are named for their discoverer, the physicist Walter Schottky. A Schottky diode consists of a metal-semiconductor junction, in which the semiconductor is usually silicon, and the metal can be, typically, silver, aluminium, gold, chromium, nickel, platinum or tungsten, or alloys of exotic metals.
The diode conducts using majority carriers, so that the forward drop is small, only about 0.2 V compared to the 0.6 V of a silicon diode. In addition, the diodes have very fast switching times, meaning that when the voltage is switched off the current also turns off with only a very small delay.
This feature makes the Schottky diode useful in RF applications such as RF demodulation and in high frequency switch-mode power supplies.
Because of the low voltage drop, the diodes also make excellent power rectifiers, particularly for high-frequency supplies, though the reverse current is too high for some applications.
Figure 5.4a shows the relevant symbol.
Schottky diodes are also used embedded into ICs (see later) in logic circuits, and as part of complex devices ranging from photodiodes to MOSFETs.
Silicon carbide Schottky diodes are now being used for high-current diodes with very high voltage ratings (up to 1200 V).
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