How to distinguish between zener diode and schottky diode? — SUNMATE

Diodes are common in electronic components. Zener diodes and Schottky diodes are widely used in various industries. In the work, we often encounter customers who can't distinguish the zener diode from the schottky diode. Maybe they are just purchasing products, not engineering, so it is not surprising that they don't understand the products. So how to distinguish between zener diode and Schottky diode?

Generally, diodes are conducted in the forward direction and cut off in the reverse direction; If the reverse voltage applied to the diode exceeds the tolerance of the diode, the diode will be broken down. Zener diode is a phenomenon that the current can change in a large range while the voltage is basically unchanged by using the reverse breakdown state of the pn junction. At the breakdown point, the reverse resistance decreases to a small value. In this low resistance area, the current increases while the voltage remains constant. The zener diodes are graded according to the breakdown voltage. Because of this feature, the zener is mainly used as a voltage regulator or voltage reference element.

Schottky diode is a semiconductor device with low power consumption, high current and ultra-high speed. Its specialty is that the switching speed is very fast, the reverse recovery time can be as small as several nanoseconds, the forward conduction voltage drop is only about 0.4V, and the rectifier current can reach thousands of amperes. Therefore, it is suitable for working under the condition of low voltage and large current. Schottky diodes are used as the output rectifier diodes of the computer host power supply.

Schottky diode takes N-type semiconductor as substrate, and forms N-epitaxial layer with arsenic as dopant on it. The positive (barrier) metal material is molybdenum,. Silicon dioxide is used to eliminate the electric field in the edge area and improve the withstand voltage of Schottky diode. The doping concentration of the N-type substrate is 100 times higher than that of the N-layer, and it has a very small on state resistance. The N+cathode layer at the bottom of the substrate is used to reduce the contact resistance of the cathode. By adjusting the structural parameters, a suitable Schottky diode can be formed between the substrate and the anode metal.