11.14 : Schottky Barrier Diode

Schottky barrier diodes are specialized semiconductor devices characterized by their unique construction. This construction involves combining a metal layer with a moderately doped n-type semiconductor material. This combination leads to the formation of a Schottky barrier, a pivotal element that defines the diode's operational characteristics. The core functionality of Schottky barrier diodes is their capacity to allow current to flow in only one direction due to their distinctive metal-semiconductor junction construction.

A charge transfer occurs when the metal comes into contact with a semiconductor. This process aligns the Fermi levels of the two materials, which, depending on the initial Fermi level of the semiconductor relative to the metal, results in the formation of a depletion region around the contact area. In n-type semiconductors, this depletion region is populated with positive charges from donor ions that are uncompensated, whereas, in p-type semiconductors, the depletion region contains negative charges, thus ensuring the diode's directionality in current flow.

The Schottky barrier diode distinguishes itself from conventional pn-junction diodes through its operational speed and efficiency. Since it operates primarily through majority carriers and lacks minority-carrier charge-storage effects, it is significantly faster, making it ideal for switching applications. Additionally, the forward voltage drop across a Schottky diode is lower than pn-junction diodes, which leads to reduced power dissipation during operation.

With these characteristics, Schottky diodes are extensively utilized in applications requiring fast switching and low power loss, such as voltage clamping and transient protection circuits. Their rapid response and low forward voltage make them an indispensable component in modern electronic circuit design, especially where efficiency and speed are critical parameters.