After the invention of the first semiconductor device, many great scientists investigated the properties of the pn junction. As you may have guessed, this is a regular diode, which can be seen in any electronic circuit. At the time of his invention, it was an element that made a real revolution and changed all ideas about the future of electronics. Also, the technology of its manufacture did not go unnoticed. A Zenner and Gunn diode appeared. The Schottky diode was also invented,
having interesting properties. Its use in electronics was not as sensational as that of its famous “brothers”. The special properties of this element were previously used in highly specialized schemes and were not widely used. It is all the more interesting that in recent years, the Schottky diode began to be used as the main element in switching power supplies. It works in almost all electronic household appliances: televisions, tape recorders, personal computers, laptops, etc.
The special properties of the device are manifested in a low voltage drop at the pn junction. It does not exceed 0.4 Volts. That is, in this parameter it is as close as possible to the ideal element that is used in the calculations. True, at voltages of more than 50 volts, these properties disappear. Nevertheless, the Schottky diode has become widely used in circuits with
operational amplifiers. The power supply of such circuits did not exceed 15 volts of direct voltage, which made it possible to fully use the properties of this device. He could stand in the feedback circuit as a restrictive element or participate in the work of regulators.
In addition to such an important property as
the voltage drop at the pn junction, the Schottky diode has a small capacitance. This allows him to work in high-frequency circuits. The practically “ideal” properties of this element do not distort the high frequency signal. That is why they began to put it in switching power supplies, communication devices and regulators.
But in addition to the positive qualities, it is necessary to note the disadvantages. Schottky diodes are very sensitive even to a short-term excess of the reverse voltage from the permissible value. This leads to the failure of the element. Unlike its silicon “brothers,” it does not recover. Thermal breakdown leads either to the appearance of leakage currents, or to the “transformation” of the device into a conductor.
The first malfunction will lead to unstable operation of the entire electronic device. It is quite difficult to find and eliminate. As for thermal breakdown, for example, in a
switching power supply, this will lead to the operation of protection against
short circuit. After replacing the defective element, the power supply will work normally.
Modern industry produces quite powerful Schottky diodes. The pulse current in such devices can reach 1.2 kA. The constant operating current in some types reaches 120 A. Such devices have a wide current range and good performance characteristics. They are successfully used in household appliances and industrial electronics.