Schottky diodes, also called Schottky barrier diodes or metal–semiconductor diodes, are designed for efficiency and speed. They have a lower forward voltage drop than standard silicon diodes, reducing energy loss and heat generation. Their fast switching makes them ideal for high-frequency circuits and power applications. Since they rely only on electrons, Schottky diodes respond almost instantly to current changes, making them a preferred choice in power supplies, solar inverters, automotive electronics, and RF systems.

How do regular Si diodes work?

A diode is one of the most common passive components in electronics. It acts like a one-way valve for current, allowing electricity to flow in only one direction. This makes diodes useful in controlling current in circuits, protecting components, and converting AC to DC.

Most ordinary diodes are built from silicon. They are formed by joining two types of semiconductor materials:

• n-type semiconductor – contains extra electrons (negative charge carriers).
• p-type semiconductor – contains “holes” or missing electrons (positive charge carriers).

When these two regions meet, they create a p–n junction. At this junction, excess electrons from the n-type side move into the holes of the p-type side. This forms a depletion region, an area with an internal electric field that opposes further movement of electrons. To push current through, the external voltage must be greater than this barrier. In silicon diodes, the potential barrier is typically about 0.7 V.

How the diode responds depends on the direction of the applied voltage. In forward bias, the positive terminal is connected to the p-type side (anode) and the negative terminal to the n-type side (cathode). The external voltage reduces the depletion barrier, allowing current to flow. In reverse bias, the terminals are flipped. The depletion region widens, strengthening the barrier and preventing current flow.

Physically, diodes come in different sizes but are usually enclosed in a cylindrical molding compound with a stripe on one end (negative end), and leads on both ends of the cylinder (with the exception for LEDs, or light emitting diodes). To learn more about Si diodes in-depth, you may visit our main application page on diodes.

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Schottky Diodes vs. Regular Si Diodes

Figure. Metal-Semiconductor Junction in Schottky Diodes

Figure. Forward Voltage of Regular & Schottky Diodes

Because of how Schottky diodes are structured, the forward voltage is lower compared to traditional Si diodes (0.2 ~ 0.3V) and its switching speeds are faster. Faster switching is made possible by the diode’s unipolar nature wherein there is no accumulation of minority carriers, which is the primary cause of delay in regular diodes with p-n junctions.

To better visualize this, imagine that regular diodes are like a busy intersection with traffic lights. When the light is green, current flows easily. But when the light changes, some "traffic" (carriers) get briefly stuck, creating a slight delay before the flow can reverse.

Schottky diodes, however, are a one-way street for current. Because of their unique metal-to-semiconductor junction, they have no "traffic lights" or stranded carriers. This allows for instantaneous switching and significantly faster performance, making them ideal for high-frequency applications.

While Schottky diodes may seem like an upgrade from regular silicon diodes, it also has its fair share of disadvantages:

With how Schottky diodes are designed, they are also smaller and more compact compared to ordinary Si diodes. This is important, especially for applications where portability, space-saving, and integrability are crucial.

Applications of Schottky Diodes

Schottky diodes are ideal for applications focused on low forward voltage requirements, including the following:

• Switch-mode power supplies (SMPs) - this diode is usually a rectifier in power supplies with high efficiency & DC-DC voltage converters. Schottky diodes make the SMPs more efficient and reduces heat loss. SMPs are commonly found in inverters.  

• Blocking diode - Schottky diodes are also used as a blocking diode in photovoltaic systems for their fast switching speeds, preventing battery discharge when produced voltage is less than battery voltage.

• Voltage clamping - they are used to protect devices from reverse voltage & discharge by diverting unwanted electricity to the voltage rail, which is a line in electronics systems that can hold a certain amount of voltage and supply a small load to components without fluctuating the voltage too much. Voltage clamps with Schottky diodes are commonly used in Schottky transistors, integrated circuits, switching regulators, and digital circuits.

• Frequency mixer (also known as RF mixer) - Schottky diodes function as a frequency converter in RF mixers. Their faster switching speed and nonlinear voltage-current feature are ideal for handling the high frequencies encountered in RF applications. Schottky diodes convert the input radio frequencies to a desired intermediate frequency (IF) for further processing. RF mixers are commonly found in cell phones, radio receivers, transmitters, radar systems, spectrum analyzers and signal generators.

Design Challenges of Schottky Diodes

Aside from leakage current & lower reverse voltage, Schottky diode’s design also have the following challenges:

CAPLINQ Solutions for Schottky Diodes

Designing Schottky diodes presents challenges primarily within the die, specifically at the metal-semiconductor junction. The key is to carefully select materials with properties that are highly compatible with the die's, ensuring optimal performance and reliability.

Like any other semiconductor devices, Schottky diodes are encapsulated in an epoxy molding compound. For maximum reliability, molding compounds with high adhesion, thermal stability, and CTE matching are required. LINQSOL EMC-G135 is highly recommended for Schottky diode encapsulation.

LINQSOL EMC-G135 is a green epoxy molding compound specifically developed for rectifier bridges (GBU, KBJ, GBS and etc.) and SMX packages. It offers good moldability and low modulus to meeting low-stress requirements. With a thermal conductivity of ~1.7W/m⋅K, it satisfies the heat dissipation required by high-performing packages. G135 boasts of its high-cost effectiveness and excellent workability with more than 500 continuous mold shots. 

LINQSOL EMC-G135 guarantees strong performance and outstanding reliability. This product is deliberately formulated without the inclusion of substances prohibited by the European Union RoHS and REACH. LINQSOL EMC-G135 seamlessly integrates advanced material properties, safety compliance, and superior performance to deliver a reliable solution for semiconductor device encapsulation.

Selecting the right die attach material is also crucial in Schottky diode packaging. CAPLINQ provides a wide range of Die Attach Materials designed for various applications. Our selection includes high-conductivity epoxies, precision solders, and films. These materials ensure excellent thermal management and reliable electrical performance for your power devices, RF components, and microelectronics.microelectronics. Contact us for specialized technical support.