The correct answer is option 'C', which is the Schottky diode.

Schottky diodes are a type of diode that use a metal-semiconductor junction. They are named after the German physicist Walter H. Schottky, who first described this type of diode in the early 1930s. Schottky diodes are widely used in various electronic applications due to their unique characteristics and advantages.

Now, let's discuss in detail about Schottky diodes and the metal-semiconductor junction.

The Schottky diode:
A Schottky diode is a semiconductor device with a low forward voltage drop and fast switching characteristics. It is formed using a metal-semiconductor junction instead of the P-N junction found in other diodes. The metal used in the junction is typically a low-work-function metal such as platinum or tungsten.

Metal-semiconductor junction:
In a metal-semiconductor junction, the metal and the semiconductor come into contact to form a junction. Unlike the P-N junction in other diodes, there is no depletion region or built-in potential barrier at the metal-semiconductor junction. This results in a lower forward voltage drop compared to P-N junction diodes.

Advantages of Schottky diodes:
1. Low forward voltage drop: The absence of a depletion region at the metal-semiconductor junction allows Schottky diodes to have a lower forward voltage drop compared to other diodes. This makes them suitable for applications where low power losses are desired.
2. Fast switching speed: Due to the absence of a depletion region, Schottky diodes have a faster switching speed compared to P-N junction diodes. This makes them ideal for high-frequency applications.
3. Low reverse recovery time: Schottky diodes have a very short reverse recovery time, which means they can quickly switch from the conducting state to the non-conducting state. This property is beneficial in applications where fast turn-off is required.

Applications of Schottky diodes:
Schottky diodes find applications in various electronic circuits, including:
1. Power rectification: Schottky diodes are commonly used in power rectification circuits due to their low forward voltage drop and fast switching characteristics.
2. Switching power supplies: They are used in switching power supplies to reduce power losses and improve efficiency.
3. RF and microwave circuits: Schottky diodes are suitable for high-frequency applications, such as RF mixers and detectors, due to their fast switching speed.
4. Voltage clamping circuits: They can be used in voltage clamping circuits to protect sensitive components from voltage spikes.

In conclusion, the Schottky diode is the correct answer as it uses a metal-semiconductor junction, which distinguishes it from other diodes such as general-purpose diodes or fast recovery diodes. The metal-semiconductor junction in the Schottky diode provides advantages such as a low forward voltage drop, fast switching speed, and low reverse recovery time, making it suitable for various electronic applications.