Application advantages of Schottky diodes

Application advantages of Schottky diodes

     A Schottky diodes is a semiconductor component made of a metal material as the positive stage and an N-type semiconductor as the negative stage, using the potential barrier generated on the surface of the two to have the characteristics of a rectifier. It is a hot carrier diode , Schottky diodes are mainly used as rectifier diodes, freewheeling diodes, maintenance diodes, etc. in power circuits, and are mainly used in low-voltage, high-current power circuits, such as power transformers, soft starters, inverter power supplies, and optical fiber communications. . It is widely used in small signal circuits of semiconductor radios, tape recorders, televisions and communication equipment. Today we will take a look at the application advantages of Schottky diodes in circuits:

Schottky diodes

     Schottky diodes are precious metals such as gold, silver, aluminum, platinum, etc. as the positive stage, and N-type semiconductor B as the negative stage. The metal material-semiconductor components are made by using the potential barrier generated on the surface of the two to have the characteristics of a rectifier. . Since there are many electronic devices in the N-type semiconductor, and there are only a small amount of free charges in the precious metal, the electronic devices diffuse from B with a high concentration to A with a low concentration.

     There is no cavitation in the metal material A, and there will be no cavitation outward diffusion movement from A to B. As the electronic devices continue to diffuse from B to A, the concentration of electronic devices on the B surface gradually decreases, and the surface charge balance is destroyed, so a potential barrier is generated, and the direction of the electric field is B→A. But in this electrostatic effect, the electronic device in A will also produce a drifting motion from A→B, thereby weakening the electrostatic field generated due to the diffusion motion. When a space charge region of a certain width is established, the electron drift movement caused by the electrostatic field and the electron diffusion movement caused by different concentrations are relatively balanced, forming a Schottky barrier.

     The internal power circuit structure of a typical Schottky rectifier is based on an N-type semiconductor substrate, on which an N-epitaxial layer using arsenic as a dopant is produced. Anodizing uses raw materials such as molybdenum or aluminum to make the barrier layer. Use silicon dioxide (SiO2) to eliminate the electrostatic field in the edge area and increase the pressure resistance of the water pipe.

     The N-type substrate has a small on-state resistance, and its inclusion concentration is 100% higher than that of the H-layer. An N+ negative electrode layer is created under the substrate, the effect of which is to reduce the loop resistance of the negative electrode. According to the main parameters of the optimized structure, a Schottky barrier is formed between the N-type substrate and the anodized metal material, as shown in the figure below. When a forward bias is added on both sides of the Schottky barrier (the positive pole of the anodized metal material is inserted, and the negative pole of the N-type substrate is inserted), the Schottky barrier layer becomes smaller and its internal resistance shrinks; on the contrary , if the Schottky barrier layer is added with a reverse bias on both sides, the Schottky barrier layer becomes larger and its internal resistance increases.