Schottky diodes are named after their inventor Dr. Schottky, also known as Schottky barrier diodes, SBD is short for Schottky barrier diodes. So what is the principle of Schottky diodes? Let's take a look.
Schottky diode SBD is not the use of P-type semiconductor and N-type semiconductor contact PN junction principle of production, but the use of metal and semiconductor contact formed by the principle of metal - semiconductor junction made.
Schottky diodes are metal-semiconductor devices in which the noble metal (gold, silver, aluminum, platinum, etc.) is a positive electrode and the N-type semiconductor B is a negative electrode. The Schottky diode is formed by utilizing the potential barrier formed on the contact surface. Because there are a large number of electrons in N-type semiconductors and only a very small amount of free electrons in the noble metal, the electrons diffuse from high-concentration B to low-concentration A atoms. Obviously, there is no hole in the metal A, there is no diffusion of holes from A to B diffusion. As the electrons continue to diffuse from B to A, the B surface electron concentration gradually decreases and the surface neutrality is destroyed. As a result, a potential barrier is formed and the electric field direction is B → A. However, under the action of the electric field, the electrons in A also produce a drift movement from A → B, thereby weakening the electric field due to the diffusion movement. When a certain area of space charge is established, the Schottky barrier is formed by a relative balance between the electron drift caused by the electric field and the electron diffusion caused by the different concentrations.
A typical Schottky rectifier has an internal circuit structure that uses an N-type semiconductor as a substrate on which an N-epitaxial layer with arsenic as a dopant is formed. The anode is made of a barrier material such as molybdenum or aluminum. Silicon dioxide (SiO2) to eliminate the edge of the electric field and improve the pressure value of the tube. N-type substrate has a very small on-state resistance, the doping concentration higher than the H-layer 100% times. An N + cathode layer is formed under the substrate to reduce the contact resistance of the cathode.
Schottky diode common models SS, MBR, SR, etc., on behalf of models SS510, MBR1030, SR150 and so on.
In summary, the principle of Schottky diodes and PN junction rectifier have a great deal of difference is usually referred to as PN junction rectifier rectifier tube, and the metal - semiconductor rectifier called Schottky rectifier Tubes, silicon-on-silicon process Schottky diodes have also been introduced, which not only saves precious metals, drastically reduces costs, but also improves the consistency of the parameters.
