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First, Schottky diode introduction:
SBD is an abbreviation for Schottky Barrier Diode (abbreviated as SBD). SBD is not fabricated by the principle of forming a PN junction by contacting a P-type semiconductor with an N-type semiconductor, but by a metal-semiconductor junction principle formed by metal-to-semiconductor contact. Therefore, SBD is also called a metal-semiconductor (contact) diode or a surface barrier diode, which is a hot carrier diode.
Second, Schottky diode function:
Schottky diodes, also known as Schottky barrier diodes (SBD), are low-power, ultra-high-speed semiconductor devices. The most notable feature is that the reverse recovery time is extremely short (can be as small as a few nanoseconds), and the forward voltage drop is only about 0.4V. It is widely used as high frequency, low voltage, high current rectifier diode, freewheeling diode, protection diode, and also used as a rectifier diode and small signal detection diode in circuits such as microwave communication. It is more common in communication power supplies, inverters, etc.
A typical application is to clamp the Shockley diode on the BJT in the switching circuit of the bipolar transistor BJT, so that the transistor is in the off state when it is in the on state, thus increasing the switching speed of the transistor. This method is used in TTL internal circuits of typical digital ICs such as 74LS, 74ALS, and 74AS.
The biggest feature of Schottky diodes is that the forward voltage drop VF is relatively small. In the case of the same current, its forward voltage drop is much smaller. In addition, its recovery time is short.
Third, the characteristics of Schottky diode:
1) Since the Schottky barrier height is lower than the PN junction barrier height, its forward conduction threshold voltage and forward voltage drop are both lower (about 0.2V lower) than the PN junction diode.
2) Since SBD is a majority carrier conductive device, there is no minority carrier lifetime and reverse recovery problem. The reverse recovery time of the SBD is only the charge and discharge time of the Schottky barrier capacitor, which is completely different from the reverse recovery time of the PN junction diode. Since the reverse recovery charge of the SBD is very small, the switching speed is very fast and the switching loss is also very small, which is especially suitable for high frequency applications.
3) It is a low power, ultra high speed semiconductor device. The most notable feature is that the reverse recovery time is extremely short (can be as small as a few nanoseconds), and the forward voltage drop is only about 0.4V. The biggest feature of Schottky diodes is that the forward voltage drop VF is relatively small. In the case of the same current, its forward voltage drop is much smaller. In addition, its recovery time is short. It also has some disadvantages: low withstand voltage and large leakage current. It is widely used as high frequency, low voltage, high current rectifier diode (such as switching power supply secondary rectifier diode), freewheeling diode, protection diode, also used as a rectifier diode, small signal detection diode in microwave communication and other circuits. It is more common in communication power supplies, inverters, etc.
Fourth, Schottky diode application:
It is a low-power, ultra-high-speed semiconductor device widely used in switching power supplies, inverters, drivers and other circuits for high-frequency, low-voltage, high-current rectifier diodes, freewheeling diodes, protection diodes, or in microwave communications. It is used as a rectifier diode and a small signal detection diode in the circuit.
Five, Schottky diode working principle:
The Schottky diode is a metal-semiconductor device in which a noble metal (gold, silver, aluminum, platinum, etc.) A is a positive electrode, and an N-type semiconductor B is a negative electrode, and a barrier formed on the contact surface thereof has a rectifying property. Since there are a large number of electrons in the N-type semiconductor, and there is only a very small amount of free electrons in the noble metal, the electrons diffuse from the high concentration B to the low concentration A. Obviously, there is no hole in the metal A, and there is no diffusion movement of holes from A to B. As electrons continue to diffuse from B to A, the electron concentration on the B surface gradually decreases, and the surface electrical neutrality is destroyed, thus forming a potential barrier whose electric field direction is B→A. However, under the action of the electric field, the electrons in A also produce a drift motion from A→B, thereby weakening the electric field formed by the diffusion motion. When a space charge region of a certain width is established, the electron drift caused by the electric field and the electron diffusion motion caused by the difference in concentration reach a relative balance, and a Schottky barrier is formed.