Schottky diode :
it is a semiconductor diode formed by the junction of a semiconductor with a metal. It has a low forward voltage drop and a very fast switching action. The cat’s-whisker detectors used in the early days of wireless and metal rectifiers used in early power applications can be considered primitive Schottky diodes.
- It is also known as hot carrier diode.
- schottky diode is named after a German physicist “Walter H.Schottky”
A metal–semiconductor junction is formed between a metal and a semiconductor, creating a Schottky barrier. Typical metals used are molybdenum, platinum, chromium or tungsten, and certain silicides ,whereas the semiconductor would typically be n-type silicon. The metal side acts as the anode, and n-type semiconductor acts as the cathode of the diode. This Schottky barrier results in both very fast switching and low forward voltage drop.
Reverse current and discharge protection
Switched-mode power supplies
The most evident limitations of Schottky diodes are their relatively low reverse voltage ratings, and their relatively high reverse leakage current. For silicon-metal Schottky diodes, the reverse voltage is typically 50 V or less. Some higher-voltage designs are available (200 V is considered a high reverse voltage). Reverse leakage current, since it increases with temperature, leads to a thermal instability issue. This often limits the useful reverse voltage to well below the actual rating.
While higher reverse voltages are achievable, they would present a higher forward voltage, comparable to other types of standard diodes. Such Schottky diodes would have no advantage unless great switching speed is required.