Schottky Barrier Rectifiers Working and Its Applications

The Schottky diode or Schottky Barrier Rectifier is named after the German physicist “Walter H. Schottky”, is a semiconductor diode designed with a metal by the semiconductor junction. It has a low-forward voltage drop and a very rapid switching act. In the early days of wireless, cat’s-whisker detectors are used and in early power applications, metal rectifiers used which can be measured primitive Schottky diodes. Despite the fact that, in today’s high tech electronics prospect these diodes have several applications. Actually, it is one of the oldest semiconductor devices in reality. As a metal-semiconductor device, its applications can be traced back to before 1900 where crystal detectors, cat’s whisker detectors and the like were all effectively Schottky barrier diodes.

Schottky Barrier Rectifier?

The Schottky Barrier rectifier diode is an electronic component that is generally used in RF applications like a mixer or detector diode. This diode is also used in power applications like a rectifier because of its features like its low forward voltage drop important to lower levels of power loss contrasted to normal PN junction diodes.

The symbol of the Schottky diode is similar to the basic diode circuit symbol. This diode symbol is distinguished from other kinds of the diode by the adding of the two additional legs on the bar on the symbol.

Construction of Schottky Barrier Diode

In this diode, connection created between metal and semiconductor to form Schottky barrier i.e. metal side performs as an anode and n-type semiconductor works as a cathode. The selection of the combination of the metal and semiconductor decides the forward voltage of the diode. Both p-type and n-type semiconductor can increase Schottky barriers but p-type semiconductor has a low forward voltage contrast to the n-type semiconductor.

As we know that, a forward voltage is inversely proportional to outflow current that is if this voltage is low then the reverse outflow current is high which is not preferable. That’s why we are using n-type semiconductor material in this diode. Typical metals used in the assembly of Schottky barrier diode are platinum, tungsten or chromium, molybdenum, palladium silicide, platinum silicide, gold etc.

Working of Schottky Barrier Diode

As shown in the below figure, when the voltage is applied to the diode in such a way that the metal is +Ve with respect to the semiconductor. It is a unipolar device as it has electrons as majority charge carriers on both sides of the junction. When these two are brought in contact, electrons begin to flow in both directions across the metal-semiconductor interface.

Therefore there are no depletion region shapes near the junction that is, there is no large current from the metal to the semiconductor in reverse bias. Due to the time of electron-hole recombination, the delay there in the junction diodes is not present. N-type semiconductors have superior potential energy as a contrast to electrons of metals. The voltage increased across the diode will be against the built-in potential and makes simple to the flow of current.

Advantages and Disadvantages

Schottky diodes are used in a lot of applications where other kinds of the diode will not execute as well. They offer a number of advantages that include the following.

• Low turn-on voltage
• Fast recovery time
• Low junction capacitance
• High efficiency and High current density
• These diodes work at high frequencies.
• These diodes generate less unnecessary noise than P-N junction diode
• The main disadvantage of Schottky diode is, it generates large reverse saturation current than the p-n junction diode

V-I Characteristics

• The V-I characteristics of Schottky diode are shown in the figure below. The vertical line in the figure signifies the flow of current in the diode and the Horizontal line signifies the voltage applied across the diode.
• The V-I characteristics of this diode are approximately related to the P-N junction diode. But, the forward voltage drop of this diode is very little as contrasted to the P-N junction diode.
• The forward voltage drop of Schottky diode ranges from 0.2 to 0.3 volts whereas the forward voltage drop of silicon P-N junction diode ranges from 0.6 to 0.7 volts.
• If the forward bias voltage is superior to 0.2 or 0.3 volts, then the flow of current starts flowing through the diode.
• In this diode, the reverse saturation current happens at a very low-voltage as contrasted to the silicon diode.

Applications of Schottky Diode

Schottky diodes are used for many purposes which include the following

• Schottky diodes are used as rectifiers in high power application circuits
• Schottky diodes are used in various applications like RF, power, detect signal, logic circuits
• Schottky diodes play an essential role in GaAs circuits
• Schottky diodes used in the stand-alone PV (photovoltaic) system to stop batteries from discharging through the solar panels at nighttime as well as in the network connection system.
• Schottky diodes are used in voltage clamping applications.

Thus, this is all about Schottky Barrier Rectifiers Working and Its Applications. We hope that you have got a better understanding of this concept. Furthermore, for any doubts regarding this article or to implement any electrical projects please give your valuable suggestions in the comment section below. Here is a question for you, what is the main function of Schottky diode?