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The Fundamentals of Silicon Carbide Schottky Diodes

Nov 08, 2019
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The Fundamentals of Silicon Carbide Schottky Diodes

In the last blog, we looked at the durability of SiC. In this blog, we will take a look at the properties and performance of SiC Schottky diodes, including a review of what makes Schottky diodes different and how they work. 

What Makes a Schottky Diode Different

In the typical diode, a p-n junction is formed by combining p-type and n-type semiconductors. Schottky diodes are different, however: metal is used in place of the p-type semiconductor. Then, instead of a p-n junction, you have an m-s junction known as the Schottky Barrier (which is where these diodes get their name).

How Schottky Diodes Work

How a Schottky diode works depends on whether it’s in an unbiased, forward-biased, or reverse-biased state. When a Schottky diode is in an unbiased state, the free electrons will move from the n-type semiconductor to the metal. This forms a barrier where the positive and negative electrons meet, and any free electrons are going to need energy other than their built-in voltage to successfully overcome this barrier.

In the case of a forward-biased state, electrons can cross the barrier if the voltage is greater than 0.2 V. On the other hand, with a reverse-biased state, the barrier is actually expanded and an electric current is prevented. But there is a catch: if the reverse bias voltage keeps increasing, it can break down the barrier and cause damage.

The Benefits of Schottky Diodes

One of the most well-known benefits of a Schottky diode is the fact that it consumes less voltage than a standard diode, resulting in a low forward voltage drop and leaving more voltage to actually power the load. Because these diodes consume less power, they work extremely well for low-voltage applications. They are also known for their high switching speeds because the small amount of charge that remains stored within the diode lends itself to faster recovery time. And, last but not least, Schottky diodes generate less EMI noise during switching.

SiC Schottky Diodes Performance

The use of SiC with an MPS (merged-PiN Schottky) design takes advantage of the natural durability of SiC to provide a more robust, reliable, and rugged alternative to traditional Si designs. SiC Schottky diodes have better conductivity (both electrical and thermal) than their Si counterparts. These combined properties make it possible to achieve a low forward voltage drop across the entire operating temperature range of the diode, not over just a small portion. The MPS design enabled by SiC makes it possible to achieve a higher forward current-carrying capacity. The SiC Schottky diodes also have a higher breakdown voltage and better surge capability than Si models.

SiC Schottky diodes have found many different applications, mainly in power electronics. They can be found in applications related to solar cells, electric and hybrid vehicle power systems, radio frequency detectors, power rectifier circuits, and industrial power. Wolfspeed has specialized in the development of SiC Schottky diodes and their 6th generation design is ready for you to implement in your own designs.

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