What is Schottky diode

With the continuous advancement of technology, Schottky diodes have been widely used in fields such as lighting, automotive electronics, and smart meters. However, due to its small size, many people have not paid attention to its function.

Schottky Barrier Diode (SBD) is a low-power, high current, and ultra high speed semiconductor device that has emerged in recent years. Its reverse recovery time is extremely short (can be as small as a few nanoseconds), with a forward conduction voltage drop of only about 0.4V, while the rectified current can reach several thousand amperes. These excellent features are incomparable to fast recovery diodes. Most medium and low-power Schottky rectifier diodes are packaged.

Schottky Barrier Diode is a diode with Schottky characteristics and a "metal semiconductor junction". Its forward starting voltage is relatively low. In addition to tungsten material, its metal layer can also be made of materials such as gold, molybdenum, nickel, titanium, etc. Its semiconductor materials are made of silicon or gallium arsenide, mostly type semiconductors. This device is conducted by majority carriers, so its reverse saturation current is much larger than that of PN junctions conducted by minority carriers.

Due to the minimal storage effect of minority carriers in Schottky diodes, their frequency response is only limited by the RC time constant, making them an ideal device for high-frequency and fast switching. Its operating frequency can reach 100GHz. And MIS (metal insulator semiconductor) Schottky diodes can be used to make solar cells or light-emitting diodes.

Schottky diodes: Schottky diodes control current by utilizing the potential barrier formed by the contact between metal and semiconductor. Its main feature is having a low forward voltage drop (0.3V to 0.6V); In addition, it is a multi carrier participating in conduction, which has a faster reaction speed than few carrier devices. Schottky diodes are commonly used in gate circuits as clamping diodes for the collector of transistors to prevent the switching speed from decreasing due to the transistor entering saturation state.

In summary, the structural principle of Schottky rectifiers is significantly different from that of PN rectifiers. PN rectifiers are commonly referred to as junction rectifiers, while metal semiconductor rectifiers are called Schottky rectifiers. In recent years, aluminum silicon Schottky diodes manufactured using silicon planar technology have also been introduced, which not only saves precious metals and significantly reduces costs, but also improves parameter consistency.

The Schottky rectifier uses only one type of carrier (electron) to transport charges, and there is no accumulation of excess minority carriers outside the barrier. Therefore, there is no charge storage problem (Qrr → 0), which significantly improves the switching characteristics. Its reverse recovery time can be shortened to within 10ns. But its reverse withstand voltage value is relatively low, generally not exceeding 100V when it goes out. Therefore, it is suitable for working under low voltage and high current conditions. By utilizing its low voltage drop characteristic, the efficiency of low voltage and high current rectification (or freewheeling) circuits can be improved.