Schottky diode characteristics

　　Schottky diode is a kind of semiconductor device with low power consumption, high current and ultra-high speed. Its reverse recovery time can be as short as a few nanoseconds, the forward conduction voltage drop is only about 0.4v, and the rectified current can reach several thousand amps.In the long run, Integrated Circuits (ICs) The value will be higher and higher, and there will be a great leap in essence. https://www.xinyun-ic.com/

　　Schottky diode is a metal-semiconductor device made of noble metal (gold, silver, aluminum, platinum, etc.) A as the positive electrode and N-type semiconductor B as the negative electrode, and the barrier formed on the contact surface between them has rectification characteristics. Because there are a lot of electrons in N-type semiconductors and only a few free electrons in precious metals, electrons diffuse from B with high concentration to A with low concentration. Obviously, there are no holes in metal A, so there is no diffusion movement of holes from A to B. With the continuous diffusion of electrons from B to A, the electron concentration on the surface of B gradually decreases, and the surface electrical neutrality is destroyed, so a potential barrier is formed, and its electric field direction is B ★ A. However, under the action of this electric field, the electrons in A will also drift from A to B, thus weakening the electric field formed by diffusion movement. When a space charge region with a certain width is established, the electron drift motion caused by electric field and the electron diffusion motion caused by different concentrations reach a relative balance, and a Schottky barrier is formed.

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　　Schottky barrier diode (SBD) has the advantages of high switching frequency and low forward voltage, but its reverse breakdown voltage is relatively low, mostly not higher than 60V, and the highest is only about 100V, which limits its application range. For example, in switching power supply (SMPS) and power factor correction (PFC) circuits, freewheeling diodes of power switching devices, high-frequency rectifier diodes of more than 100V for transformer secondary, high-speed diodes of 600V~1.2kV in RCD buffer circuits, and 600V diodes for PFC boost, only fast recovery epitaxial diodes (FRED) and ultra-fast recovery diodes (UFRD) are used. At present, the reverse recovery time Trr of UFRD is also above 20ns, which can not meet the needs of SMPS with 1MHz~3MHz in fields such as space station. Even for SMPS with hard switch of 100kHz, due to the high conduction loss and switching loss of UFRD and high shell temperature, a large radiator is needed, which increases the size and weight of SMPS, which is not in line with the development trend of miniaturization and thinness. Therefore, the development of high voltage SBD above 100V has always been a research topic and a hot spot of concern. In recent years, SBD has made a breakthrough, with 150V and 200V high-voltage SBD on the market, and more than 1kV SBD made of new materials has also been successfully developed, thus injecting new vitality into its application.