11.14 : ショットキーバリアダイオード

Schottky barrier diodes are semiconductor devices formed by joining a metal layer with a moderately doped n-type semiconductor material.

When a metal contacts a semiconductor, charge transfer aligns the Fermi levels.

If the semiconductor's initial Fermi level is higher than the metal's pre-contact Fermi level, it raises its potential, forming a Schottky barrier-associated depletion region.

With n-type semiconductors, this region contains positive charges from uncompensated donor ions, aligning with the metal's negative charges.

With p-type semiconductors, the process is reversed, leading to a depletion region with negative charges to match the metal's positive charges.

The metal-semiconductor junction behaves like a diode, allowing unidirectional current flow from the metal anode to the semiconductor cathode while acting as an open circuit in the other direction.

Schottky diodes primarily conduct current through majority carriers and lack minority-carrier charge-storage effects, making them faster for switching applications.

Their conducting forward voltage drop is lower than that of pn-junction diodes, reducing power dissipation.

Schottky diodes are used for voltage clamping and transient protection due to their low forward voltage and rapid response.