The Schottky diode is named after its inventor, Dr. Schottky, and SBD is short for Schottky diode (SBD). SBD does not use the principle of P-type semiconductor and N-type semiconductor contact to form a PN junction, but uses the principle of metal-semiconductor contact to form a metal-semiconductor junction. Therefore, SBD is also called a metal semiconductor (contact) diode or a surface barrier diode, which is a hot carrier diode.
Schottky diodes are metal semiconductor devices made of precious metals (gold, silver, aluminum, platinum, etc.). ) A is used as the positive electrode, and the N-type semiconductor B is used as the negative electrode, and uses the rectifying characteristics of the barrier formed on the contact surface of the two. Because there are a large number of electrons in N-type semiconductors and only a very small amount of free electrons in precious metals, electrons diffuse from a high concentration of B to a low concentration of A. Obviously, there are no holes in metal A, so there is no diffusion movement of holes from A to B. As the electrons continue to diffuse from B to A, the concentration of electrons on the surface of B gradually decreases, and the electrical neutrality of the surface is destroyed, thus forming a barrier with the electric field direction of B A. However, under the action of this electric field, the electrons in A will also produce a drift movement from A to B, thereby weakening the electric field formed by the diffusion movement. When a space charge region with a certain width is established, the drifting movement of electrons caused by the electric field and the diffusion movement of electrons caused by different concentrations reach a relative balance, thus forming a Schottky barrier.
The internal circuit structure of a typical Schottky rectifier is based on an N-type semiconductor on which an N epitaxial layer doped with arsenic is formed. The anode is made of molybdenum or aluminum and other materials to form a barrier layer. Silica (silicon dioxide) is used to eliminate the electric field in the edge area and improve the pressure resistance of the tube. The N-type substrate has a very small on-resistance, and its doping concentration is 100% higher than that of the H layer. A nitrogen cathode layer is formed under the substrate to reduce the contact resistance of the cathode. As shown in the figure, by adjusting the structural parameters, a Schottky barrier is formed between the N-type substrate and the anode metal. When a forward bias voltage is applied to both ends of the Schottky barrier (the anode metal is connected to the anode of the power supply, and the N-type substrate is connected to the cathode of the power supply), the Schottky barrier layer becomes narrower, and Its internal resistance becomes smaller. On the other hand, if a reverse bias is applied to both ends of the Schottky barrier, the Schottky barrier layer becomes wider and its internal resistance becomes larger.
The structure principle of Schottky rectifier is very different from PN junction rectifier. The PN junction rectifier is usually called the junction rectifier, and the metal half-conductor rectifier is called the Schottky rectifier. Aluminum-silicon Schottky diodes made with silicon planar technology have also come out. It not only saves precious metals, greatly reduces costs, but also improves the consistency of parameters.
The above explanation is the origin of the naming of Schottky diodes. I hope it will be helpful to you after reading. If you want to know more about Schottky diodes, please contact customer service online or call our company’s service Hotline (upper right corner of the website) for consultation, we will be happy to provide you with quality service!