#Definition of Diode:
A diode is a specialized electronic component with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium. Some diodes are comprised of metal electrodes in a chamber evacuated or filled with a pure elemental gas at low pressure. Diodes can be used as rectifiers, signal limiters, voltage regulators, switches, signal modulators, signal mixers, signal demodulators, and oscillators.
The fundamental property of a diode is its tendency to conduct electric current in only one direction. When the cathode is negatively charged relative to the anode at a voltage greater than a certain minimum called forward breakover, then current flows through the diode. If the cathode is positive with respect to the anode, is at the same voltage as the anode, or is negative by an amount less than the forward breakover voltage, then the diode does not conduct current. This is a simplistic view, but is true for diodes operating as rectifiers, switches, and limiters. The forward breakover voltage is approximately six tenths of a volt (0.6 V) for silicon devices, 0.3 V for germanium devices, and 1 V for selenium devices.
Semiconductor diodes can be designed to produce direct current (DC) when visible light, infrared transmission (IR), or ultraviolet (UV) energy strikes them. These diodes are known as photovoltaic cells and are the basis for solar electric energy systems and photosensors. Yet another form of diode, commonly used in electronic and computer equipment, emits visible light or IR energy when current passes through it. Such a device is the familiar light-emitting diode (LED).
#Types of diodes
There are following major types of Diodes
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#Gunn Diode: Gunn diode is fabricated with n-type semiconductor material only. The depletion region of two N-type materials is very thin. When voltage increases in the circuit the current also increases. After certain level of voltage the current will exponentially decrease thus this exhibits the negative differential resistance.
It has two electrodes with Gallium Arsenide and Indium Phosphide due to these it has negative differential resistance. It is also termed as transferred electron device. It produces micro wave RF signals so it is mainly used in Microwave RF devices. It can also use as an amplifier. The symbol of Gunn diode is shown below:
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#Laser Diode: - Similar to LED in which active region is formed by p-n junction. Electrically laser diode is p-i-n diode in which the active region is in intrinsic region. Used in fiber optic communications, barcodereaders, laser pointers, CD/DVD/Blu-ray reading and recording, Laser printing.
Laser Diode Types:
Double Heterostructure Laser: Free electrons and holes available simultaneously in the region.
Quantum Well Lasers: lasers having more than one quantum well are called multi quantum well lasers.
Quantum Cascade Lasers: These are heterojunction lasers which enables laser action at relatively long wavelengths.
Separate Confinement Heterostructure Lasers: To compensate the thin layer problem in quantum lasers we go for separate confinement heterostructure lasers.
Distributed Bragg Reflector Lasers: It can be edge emitting lasers or VCSELS.
#Light emitting diodes: The light emitting diode or LED is one of the most popular types of diode. When forward biased with current flowing through the junction, light is produced. The diodes use component semiconductors, and can produce a variety of colors, although the original color was red. There are also very many new LED developments that are changing the way displays can be used and manufactured. High output LEDs and OLEDs are two examples.
Earlier they used in inductor lamps but now in recent applications they are using in environmental and task handling. Mostly used in applications like aviation lighting, traffic signals, camera flashes.
#Photodiode: The photo-diode is used for detecting light. It is found that when light strikes a PN junction it can create electrons and holes. Typically photo-diodes are operated under reverse bias conditions where even small amounts of current flow resulting from the light can be easily detected. Photo-diodes can also be used to generate electricity. For some applications, PIN diodes work very well as photodetectors.
#PIN Diode:-The improved version of the normal P-N junction diode gives the PIN diode. In PIN diode doping is not necessary. The intrinsic material means the material which has no charge Carrie.
#The diode is characterized by
• Leakage current
• Maximum reverse stand-off voltage
• Breakdown voltage
• Clamping voltage
• Parasitic capacitience
• Parasitic inductance
• Amount of energy it can absorb
#Crystal Diode:-This is also known as Cat’s whisker which is a type of point contact diode. Its operation depends on the pressure of contact between semiconductor crystal and point.
In this a metal wire is present which is pressed against the semiconductor crystal. In this the semiconductor crystal acts as cathode and metal wire acts as anode. These diodes are obsolete in nature. Mainly used in microwave receivers and detectors.
• Crystal Diode Applications
1. Crystal diode rectifier
2. Crystal diode detector
3.Crystal radio receiver
#Silicon Controlled Rectifier Diode:-It consists of three terminals they are anode, cathode and a gate. It is nearly equal to the Shockley diode. As its name indicates it is mainly used for the control purpose when small voltages are applied in the circuit. The symbol of the Silicon Controlled Rectifier is as shown below:
Modes of Operation:
1. Forward blocking mode (off state): In this j1 and j3 forward biased and j2 is reverse biased. It offers high resistance below breakover voltage and hence it is said to be off state.
2. Forward conduction mode (on state): By increasing the voltage at anode and cathode or by applying positive pulse at the gate we can turn ON. To turn off the only way is to decrease the current flowing through it.
3. Reverse blocking mode (off state): SCR blocking the reverse voltage is named as asymmetrical SCR. Mostly used in current source inverters.
#Vacuum Diodes:-Vacuum diodes consist of two electrodes which will acts as an anode and the cathode. Cathode is made up of tungsten which emits the electrons in the direction of anode. Always electron flow will be from cathode to anode only. So, it acts like a switch.
The symbol is as shown in figure:
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If the cathode is coated with oxide material then the electrons emission capability is high. Anode is a bit long in size and in some cases their surface is rough to reduce the temperatures developing in the diode. The diode will conduct in only one case that is when the anode is positive regarding to cathode terminal.
#Backward diode: This type of diode is sometimes also called the back diode. Although not widely used, it is a form of PN junction diode that is very similar to the tunnel diode in its operation. It finds a few specialist applications where its particular properties can be used.
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#BARITT diode: This form of diode gains its name from the words Barrier Injection Transit Time diode. It is used in microwave applications and bears many similarities to
The more widely used IMPATT diode.
A diode is a specialized electronic component with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium. Some diodes are comprised of metal electrodes in a chamber evacuated or filled with a pure elemental gas at low pressure. Diodes can be used as rectifiers, signal limiters, voltage regulators, switches, signal modulators, signal mixers, signal demodulators, and oscillators.
The fundamental property of a diode is its tendency to conduct electric current in only one direction. When the cathode is negatively charged relative to the anode at a voltage greater than a certain minimum called forward breakover, then current flows through the diode. If the cathode is positive with respect to the anode, is at the same voltage as the anode, or is negative by an amount less than the forward breakover voltage, then the diode does not conduct current. This is a simplistic view, but is true for diodes operating as rectifiers, switches, and limiters. The forward breakover voltage is approximately six tenths of a volt (0.6 V) for silicon devices, 0.3 V for germanium devices, and 1 V for selenium devices.
Semiconductor diodes can be designed to produce direct current (DC) when visible light, infrared transmission (IR), or ultraviolet (UV) energy strikes them. These diodes are known as photovoltaic cells and are the basis for solar electric energy systems and photosensors. Yet another form of diode, commonly used in electronic and computer equipment, emits visible light or IR energy when current passes through it. Such a device is the familiar light-emitting diode (LED).
#Types of diodes
There are following major types of Diodes
Advertisement
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#Gunn Diode: Gunn diode is fabricated with n-type semiconductor material only. The depletion region of two N-type materials is very thin. When voltage increases in the circuit the current also increases. After certain level of voltage the current will exponentially decrease thus this exhibits the negative differential resistance.
It has two electrodes with Gallium Arsenide and Indium Phosphide due to these it has negative differential resistance. It is also termed as transferred electron device. It produces micro wave RF signals so it is mainly used in Microwave RF devices. It can also use as an amplifier. The symbol of Gunn diode is shown below:
Advertisement
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Laser Diode Types:
Double Heterostructure Laser: Free electrons and holes available simultaneously in the region.
Quantum Well Lasers: lasers having more than one quantum well are called multi quantum well lasers.
Quantum Cascade Lasers: These are heterojunction lasers which enables laser action at relatively long wavelengths.
Separate Confinement Heterostructure Lasers: To compensate the thin layer problem in quantum lasers we go for separate confinement heterostructure lasers.
Distributed Bragg Reflector Lasers: It can be edge emitting lasers or VCSELS.
#Light emitting diodes: The light emitting diode or LED is one of the most popular types of diode. When forward biased with current flowing through the junction, light is produced. The diodes use component semiconductors, and can produce a variety of colors, although the original color was red. There are also very many new LED developments that are changing the way displays can be used and manufactured. High output LEDs and OLEDs are two examples.
Earlier they used in inductor lamps but now in recent applications they are using in environmental and task handling. Mostly used in applications like aviation lighting, traffic signals, camera flashes.
#Photodiode: The photo-diode is used for detecting light. It is found that when light strikes a PN junction it can create electrons and holes. Typically photo-diodes are operated under reverse bias conditions where even small amounts of current flow resulting from the light can be easily detected. Photo-diodes can also be used to generate electricity. For some applications, PIN diodes work very well as photodetectors.
#PIN Diode:-The improved version of the normal P-N junction diode gives the PIN diode. In PIN diode doping is not necessary. The intrinsic material means the material which has no charge Carrie.
#The diode is characterized by
• Leakage current
• Maximum reverse stand-off voltage
• Breakdown voltage
• Clamping voltage
• Parasitic capacitience
• Parasitic inductance
• Amount of energy it can absorb
#Crystal Diode:-This is also known as Cat’s whisker which is a type of point contact diode. Its operation depends on the pressure of contact between semiconductor crystal and point.
In this a metal wire is present which is pressed against the semiconductor crystal. In this the semiconductor crystal acts as cathode and metal wire acts as anode. These diodes are obsolete in nature. Mainly used in microwave receivers and detectors.
• Crystal Diode Applications
1. Crystal diode rectifier
2. Crystal diode detector
3.Crystal radio receiver
#Silicon Controlled Rectifier Diode:-It consists of three terminals they are anode, cathode and a gate. It is nearly equal to the Shockley diode. As its name indicates it is mainly used for the control purpose when small voltages are applied in the circuit. The symbol of the Silicon Controlled Rectifier is as shown below:
Modes of Operation:
1. Forward blocking mode (off state): In this j1 and j3 forward biased and j2 is reverse biased. It offers high resistance below breakover voltage and hence it is said to be off state.
2. Forward conduction mode (on state): By increasing the voltage at anode and cathode or by applying positive pulse at the gate we can turn ON. To turn off the only way is to decrease the current flowing through it.
3. Reverse blocking mode (off state): SCR blocking the reverse voltage is named as asymmetrical SCR. Mostly used in current source inverters.
#Vacuum Diodes:-Vacuum diodes consist of two electrodes which will acts as an anode and the cathode. Cathode is made up of tungsten which emits the electrons in the direction of anode. Always electron flow will be from cathode to anode only. So, it acts like a switch.
The symbol is as shown in figure:
Advertisement
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If the cathode is coated with oxide material then the electrons emission capability is high. Anode is a bit long in size and in some cases their surface is rough to reduce the temperatures developing in the diode. The diode will conduct in only one case that is when the anode is positive regarding to cathode terminal.
#Backward diode: This type of diode is sometimes also called the back diode. Although not widely used, it is a form of PN junction diode that is very similar to the tunnel diode in its operation. It finds a few specialist applications where its particular properties can be used.
Advertisement
AliExpress.com Product - Free Shipping 1000pcs/lot 1N4007 IN4007 1A 1000V DO-41 Rectifier diode
#BARITT diode: This form of diode gains its name from the words Barrier Injection Transit Time diode. It is used in microwave applications and bears many similarities to
The more widely used IMPATT diode.
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