Introduction:
A Schottky diode is a type of diode that is constructed using a metal-semiconductor junction instead of a p-n junction. It is named after the German physicist Walter H. Schottky. The Schottky diode has several advantages over a p-n junction diode, including lower forward voltage drop, faster switching speed, and lower junction capacitance. However, it also has some disadvantages, one of which is a lower reverse voltage rating compared to a p-n junction diode of equal rating.

Explanation:
To understand why a Schottky diode has a lower reverse voltage rating, we need to look at its construction. A Schottky diode is formed by placing a metal contact on a semiconductor material, typically n-type silicon. This metal-semiconductor junction is known as a Schottky barrier.

Reverse Voltage Rating:
The reverse voltage rating of a diode refers to the maximum voltage that can be applied in the reverse direction without causing breakdown or excessive leakage current. In a p-n junction diode, the reverse voltage rating is determined by the breakdown voltage of the p-n junction, which is usually high.

Key Point:
In a Schottky diode, there is no p-n junction. Instead, the reverse voltage rating is determined by the breakdown voltage of the metal-semiconductor junction. The metal-semiconductor junction has a lower breakdown voltage compared to a p-n junction, resulting in a lower reverse voltage rating for the Schottky diode.

Key Point:
The lower reverse voltage rating of a Schottky diode makes it unsuitable for applications that require high reverse voltage capability. In such cases, a p-n junction diode with a higher reverse voltage rating would be preferred.

Conclusion:
In summary, the Schottky diode has a lower reverse voltage rating compared to a p-n junction diode of equal rating due to the construction of the metal-semiconductor junction. This lower reverse voltage rating limits the applicability of the Schottky diode in high reverse voltage applications.