Schottky Diode

What is Schottky Diode? 

A Schottky diode, widely popular as barrier diode, refers to a metal-semiconductor diode that comprises lower voltage drops than usual PN-junction diodes. On top of that, it possesses a fast switching speed. 

Their advantage includes the fact that their forward voltage drop is significantly lower than PN-junction diodes. It is because they constitute a metal electrode that links with N-type semiconductor. Contrarily, a PN-junction diode comprises P-type material and N-type material. 

In this case, a P-type semiconductor refers to an intrinsic or pure semiconductor, such as silicon or germanium. In this case, one has to add a trivalent impurity. These trivalent impurities include Boron (B), Gallium (Ga), Indium (In), and Aluminum (Al). These are also acceptor impurities. 

On the other hand, N-type materials refer to the integration of phosphorus, arsenic, antimony, and bismuth to pure semiconductors. 

How Does a Schottky Diode Function? 

A diode in this category functions as per the Schottky diode theory. It states that an essential factor in its functioning is fast switching rate and considerably lower voltage drop. 

Also, it lacks the propensity to store electrical charges at their diode junctions. One of the reasons that enable its working is the overall lack of a depletion layer. In most cases, when current passes through a diode, the terminals witness a drop in voltage. 

The drop conventionally ranges between 0.15 and 0.45 volts as opposed to an ordinary PN-junction diode. In the case of the latter, the spectrum of voltage drop is 0.6 to 1.7 volts. It happens mainly because current advances in a forward direction

Schottky diode working leverages the low voltage drop to generate a higher efficiency and output. For this to happen, the N-type semiconductor has to function as a cathode. The metal assumes the role of an anode. 

What is Schottky Diode Symbol? 

The following diagram represents the Schottky diode symbol – 

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In the above diagram, the anode section is essentially a metal, such as molybdenum, chromium, tungsten, or platinum. On the other hand, n-type semiconductors such as the integration of silicon and bismuth stand for the cathode section. 

What is Schottky Diode Construction? 

The following figure is a pictorial representation of Schottky diode construction and working –

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In this figure, you can see that a lightly doped n-type semiconductor connects to a metal electrode or the anode. Here, you can refer to the connection as ‘metal-semiconductor junction’. When current flows in a forward direction, electrons travel from the n-type material end to the metal anode. 

The drift of majority charge carriers heavily influences the overall current component passing through this category of a diode. However, such diodes also exhibit the properties of a rectifying diode. 

The primary reason behind this is that diode conduction ceases and blocks the flow of current.  It is due to the absence of p-type semiconductor. As a result, these diodes respond rapidly to reverse bias alterations. 

What are the Characteristics of a Schottky Diode? 

Since you know what is Schottky diode and its construction, it is time to move on to its characteristics. 

Therefore, Schottky diode characteristics are as follows – 

• When compared with conventional PN-junction diodes, these diodes exhibit significantly lower drops in forward voltage. 

• Forward voltage drops vary between 0.15 and 0.45 volts, as opposed to 0.6 to 1.7 volts in PN-junction diodes. 

• Forward drop in these diodes increases with the enhancement of doping concentration of N-type semiconductors. 

• The drop in forward voltage in a Schottky barrier constitutes semiconductors such as Silicon. 

• Besides, these also act as a unipolar device owing to the lack of current flow from metals to N-type conductors. 

• The implemented metals do not undergo charge storage. As a result, these switch considerably quickly with a minimum noise component. 

Furthermore, Schottky diode applications include the following – 

• Implementation in the electronics industry due to its properties as a general diode rectifier. 

• Radio Frequency (RF) applications also find broad uses of this technology. 

• These also find application in signal detection and logic circuits. 

What are the Disadvantages of a Schottky Diode? 

Despite its various uses,there are a few disadvantages of Schottky diodes. This includes – 

• High reverse current. 

• Susceptibility to leakages due to metal-semiconductor junction. 

• These cannot withstand significant reverse voltage. 

Since you are now aware of what is Schottky diode, you should check out related concepts to know a lot more about this subject. You can also download our Vedantu app to avail a convenient and interactive learning experience.