Last Updated on October 22, 2023 by Kevin Chen
When working with electronics and digital signals, you’ll come across several components that all perform some sort of filtering or separation of signal. You’ll find diodes most commonly used for this task, which is exactly why they are referred to as “diode” components. They are able to only allow current to flow in one direction due to their voltage-biased construction.
Diodes have many different types and uses; there are even various subtypes for each component. One common diode type that you will see frequently is the Shockley diode. Let’s take a closer look at what these components do and how they operate.
What is a Shockley Diode?
A Shockley diode, which is also known as PNPN diode, is a four-layer diode. This means that even though it may look like a normal PN diode, it has two extra layers. This diode has a P-type semiconductor layer, a negative N-type layer, and an N-type semiconductor layer.
The fourth layer is made up of both P and N materials, which creates a junction. A Shockley diode is also referred to as an avalanche diode since it has the ability to conduct current without any voltage applied if there is an avalanche or surge in current that passes through it.
Shockley diodes were named after William Shockley, the inventor of the transistor. It was invented in 1949 by Shockley and his team of scientists at AT&T Bell Labs. This component was created to replace vacuum tubes for use in high-frequency radio transmitters.
These components quickly became popular for use in many different applications due to their reliability and relatively low cost compared to other diodes at that time. Today these components are used in applications where high power is involved due to their ability to handle large amounts of power before bursting or failing.
How Does a Shockley Diode Work?
Shockley diodes are constructed with four layers of semiconductors that create an arrangement commonly referred to as a “sandwich” structure, which means it consists of one conductive material surrounded by another material with similar properties on both sides. This forms two junctions with layers on either side of them.
These junctions are formed by taking the P-type semiconducting material (the outermost) and placing it in between the N-type semiconducting material (the innermost).
When current is applied to the Shockley diode, it will not perform any type of conversion. Instead, this component will allow current to flow in one direction only. This is referred to as uni-directional flow. The two junctions that are created when the Shockley diode is made are referred to as PN and PN junctions.
These junctions allow for a high resistance state if they are in reverse bias or forward bias and low resistance if they are in forward bias or reverse bias.
How Does a Shockley Diode Look Like?
In terms of the physical looks or appearance, a typical Shockley diode will have a cylindrical shape. It has a metal casing, often made of tungsten, around the P-type semiconductor. The casing is shaped in a way that allows it to be easily mounted on other components in an electronic circuit.
For the size, a typical Shockley diode will have a diameter of about 1/4 inch and a length of about 10 times its diameter. This is the case for a small-signal diode. A large-signal diode, on the other hand, will have a diameter of about 0.125 inches and a length of about 6 times its diameter.
The P-type semiconductor is placed between two N-type semiconductors to form the two junctions that are needed for this component to function properly. It also contains an anode and a cathode that is connected to two different terminals or leads via wires or leads so it can be used in an electronic circuit.
When To Use A Shockley Diode?
You can use a Shockley diode in a circuit to rectify alternating current (AC). The alternating current is converted to direct current (DC) by the Shockley diode. You can use a Shockley diode in an audio amplifier to prevent oscillation of the output.
In an audio amplifier, the output signal is AC coupled. This means that it is connected to the output terminals through capacitors and inductors. The capacitors and inductors act as filters that smooth out the frequency at which the signal appears at the output. You can also use a Shockley diode in a DC power supply to convert AC into DC power for use with electronic devices or for powering other devices in battery-operated systems.
Technical Specifications of Shockley Diode
Before you buy any Shockley diode, it is vital to be fully aware of its technical specifications which include:
– Voltage Rating: This is the maximum voltage that the Shockley diode can handle before it fails.
– Power Rating: This is the maximum power that the Shockley diode can handle before it fails.
– Peak Pulse Current: This is the amount of current that a Shockley diode can handle at one time.
– Peak Repetitive Reverse Voltage: This is the maximum voltage that a Shockley diode can handle in reverse.
– Operating Temperature Range: The range of temperatures at which a Shockley diode can operate safely.
– Storage Temperature Range: The range of temperatures at which a Shockley diode can be stored safely.
-Breakdown voltage: This is the voltage where a Shockley diode fails.
– Maximum Forward Voltage: This is the voltage that the Shockley diode generates when it is forward-biased.
– Maximum Reverse Voltage: This is the maximum voltage that a Shockley diode can handle in reverse.
-Holding current: This is the amount of current that a Shockley diode requires when it is reverse-biased.
-Insulation Resistance: This is the resistance of an insulator (typically air) between two points in a circuit.
-Reverse Recovery Time: This is the amount of time necessary for a Shockley diode to recover from its forward conduction.
V-I characteristics of Shockley diode
V-I refers to the voltage ratio between the forward and reverses current. It is a measure of the performance of a Shockley diode.
The voltage-current behavior of the Shockley diode is characterized by its V-I characteristic curve. The Shockley diode has a forward bias at a given voltage and current. The current decreases as the voltage increases and the voltage increases as the current increases.
The Shockley diode is only able to handle voltages that are less than or equal to its breakdown voltage. This means that it cannot be used for circuits with high voltages or currents.
The maximum reverse recovery time of the Shockley diode is dependent on the forward recovery time of the diode and the temperature of the diode.
The breakdown voltage of a Shockley diode is dependent on its composition, size, and geometry.
Shockley Diode Circuit Diagram
The Shockley diode circuit diagram is quite simple. It is a negative voltage diode with a resistor. The resistance between the anode and cathode is called series resistance. It is used to regulate the current flowing through the diode. The voltage drop across the resistor is called the series voltage. A typical circuit for a Shockley diode is shown below:
Usage of Shockley diodes
From the working principle, it is clear that Shockley diodes are used for two main purposes. They can be used as a trigger switch or they can serve as relaxation oscillators.
When used as a trigger switch, a Shockley diode is used for a purpose of protection. In this case, the application is quite common. For example, a trigger switch is used in the emergency lighting system.
When used as a relaxation oscillator, Shockley diodes are commonly referred to as RC time constant oscillators which are widely used in the frequency control applications like radio and television receivers.
In relation to their usage, some common application areas of Shockley diodes include;
– Power semiconductor devices
– Power rectifier
– Acoustic sound and speech
– Antenna tuning
– Oscillator circuits and oscillators that use AC voltage regulation.
-Audio signal processing
-Electrical circuits and electrical power equipment
-Circuit protection in power supply systems
-Automatic control circuits and sensors.
Is Shockley diode and Schottky diode same?
Shockley diode and Schottky diode are different. The Shockley diode is made of two PN junctions separated by a thin layer of silicon dioxide and the Schottky diode is made of a single metal semiconductor PN junction diode.
Also, the Shockley diode usually works as a power switching device while the other hand Schottky diode operates as a rectifying and signaling device.
What are the advantages of a Shockley diode?
The main advantages and benefits of Shockley diodes include:
-Fast switching speed: This simply means that the time taken for the switching of the diode is very fast and this is considered to be the biggest advantage of a Shockley diode.
-Low on-resistance: Low resistance of a diode implies that the diode can be used in high-power applications where the application requires a low on resistance.
-Low on-state current: The low on-state current of a Shockley diode is the main reason behind its ability to work as a power switching device.
-Low voltage drop: This is a feature that allows the use of Schottky diodes in applications where the voltage drop across them is very small.
-Wide band gap: As we said, this diode has four layers. This automatically means that its band is quite wide. The wide band gap of a Schottky diode makes it suitable as an electrical power rectifier and this makes it suitable for use in wide range of applications that require rectification.
-Low reverse breakdown voltage: The low reverse breakdown voltage of a Schottky diode makes it suitable for use in high-power applications.
What are the disadvantages of Shockley diodes?
The main disadvantages and drawbacks of Shockley diodes include:
-High forward voltage drop: This simply means that there is too much drop across the device when it is turned ON and OFF, which may lead to some problems when used in high power applications because there will be too much loss across them during ON and OFF states.
-Low reliability: Low reliability refers to the fact that if the device fails, then it may lead to failure at any time, which may lead to problems like loss of energy supply, fire etc., but this problem can be solved by making proper modifications to such devices so that they
However, you can solve the reliability issue b buying a quality Shockley diode directly from the manufacturer.
How do I calculate the forward voltage of the Shockley diode?
To calculate the forward voltage of Shockley diode, we need to know the following parameters;
-Pentode emitter current
-Forward voltage drop per unit length of the base
-Forward voltage drop per unit length of the collector
Buying Shockley diodes
So you think you are ready to buy a Shockley diode? First, you should define what you want to use it for. Are you only interested in a diode for your experiments? Or are you looking to make a real product from it? From this, you will know the exact specifications of the diodes to buy.
You should also consider the type of device that you want to use it with. For example, if you are making your own solar cell, then a diode with a very high voltage rating is not necessary because the voltage that you will be using will be very low. On the other hand, if you want to make an LED light, then the diode that has a high voltage rating is necessary because it will have to withstand high electric current.
Also, if you are going to use it in a circuit or industrial application, then go for low-power diodes because they can handle higher voltages and currents without any problem.
Choose a reliable Shockley diode manufacturer
One important factor to consider is where you are going to buy it from. For example, if you are going to buy it from a local electronics store, then make sure that the store is reputable. Also, make sure that the price is not too expensive and that there is no problem with the product.
Even if it is importing diodes from China, ensure that you get from a reliable manufacturer or supplier. And this is where the relevance of ICRFQ comes in. We are a sourcing agent that can help you get quality electronic components such as Shockley diodes for sale in China.
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