Schottkydiódák

Schottkydiódák, or Schottky diodes, are metal–semiconductor junction diodes formed at the interface between a metal electrode and an n-type semiconductor. They are named after the German physicist Walter H. Schottky. Compared with classical p–n junction diodes, Schottky diodes conduct primarily through majority carriers, which gives them very fast switching and a low forward voltage drop. They are widely used in power electronics and RF circuits for rectification and high-speed switching.

Construction and operation: A metal contact forms a Schottky barrier with the surrounding n-type semiconductor. The barrier height depends on the metal work function and the semiconductor’s electron affinity. When a forward bias is applied, the barrier is lowered and electrons move from the semiconductor into the metal, producing current with a low forward voltage. Under reverse bias the depletion region widens and carriers are not stored in the bulk, leading to fast response but increasing leakage current with temperature.

Characteristics and limitations: The forward voltage drop is typically around 0.2–0.45 V, much lower than silicon PN diodes. Reverse leakage current increases with temperature, and the maximum reverse voltage is generally lower than for PN diodes. Schottky diodes are very fast, with negligible minority-carrier storage, but their performance can deteriorate at high temperatures due to leakage.

Applications and materials: They are common in switch-mode power supplies, DC-DC converters, and low-drop rectifiers, as well as RF detectors and clamping diodes. Silicon Schottky diodes usually employ metals such as nickel, cobalt, tungsten, or platinum on an n-type silicon substrate; higher breakdown devices and those on GaAs or SiC substrates are used for higher frequency or power.