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TYPES OF DIODE
presentation topics
Types of Diodes
There are following major types of diodes.
 The Zener Diode
 The Varactor Diode
 The Light-Emitting Diode
 The Photodiode
 The Laser Diode
 The Schottky Diode
 The PIN Diode
 The Tunnel Diode
LED
Light Emitting Diode
Light-Emitting Diode (LED)
 An LED emits light when forward-
biased.
 LEDs are available for either infrared
or visible light.
 High-intensity LEDs are used in large-
screen displays , traffic lights,
automotive lighting, and home lighting
etc.
Symbol:
Explanation:
 When the device is forward-biased, electrons
cross the pn junction from the n-type material
and recombine with holes in the p-type
material.
 The difference in energy between the
electrons and the holes corresponds to the
energy of visible light.
 When recombination takes place, the
recombining electrons release energy in the
form of photons
 The light output (both intensity and color) is
also dependent on temperature. Light
intensity goes down with higher temperature
The photo Diode
The Photo Diode:
 The photodiode is a device that
operates in reverse bias.
 The photodiode exhibits an increase in
reverse current with light intensity.
 A diode in which the reverse current
varies directly with the amount of light.
Symbol
Explanation:
 The photodiode has a small
transparent window that allows light to
strike the pn junction.
 when its pn junction is exposed to
light, the reverse current increases
with the light intensity. When there is
no incident light the reverse current,
is almost negligible and is called the
dark current.
 Some typical photodiodes are shown
in Figure
Photo diode
The Zener diode
The Zener Diode:
 A diode designed for limiting the
voltage across its terminals in reverse
bias.
 A zener diode maintains a nearly
constant voltage across its terminals
over a specified range of zener
currents.
 The zener diode operates in reverse
breakdown.
Explanation:
 A Zener diode is a silicon pn junction
device that is designed for operation in
the reverse-breakdown region. The
breakdown voltage of a zener diode is
set by carefully controlling the doping
level during manufacture. when a
diode reaches reverse breakdown, its
voltage remains almost constant even
though the current changes drastically,
and this is the key to zener diode
operation.
Continue…
 This volt-ampere characteristic is
shown again in Figure with the normal
operating region for zener diodes
shown as a shaded area.
The Varactor Diode
The Varactor Diode:
 A variable capacitance diode.
 The capacitance of a varactor varies
inversely with reverse-bias voltage
 The current regulator diode keeps its
forward current at a constant specified
value.
Symbol:
Explanation:
 A varactor is a diode that always
operates in reverse bias and is doped
to maximize the inherent capacitance
of the depletion region. The depletion
region acts as a capacitor dielectric
because of its nonconductive
characteristic. The p and n regions are
conductive and act as the capacitor
plates, as shown in figure:
The laser diode
The Laser Diode:
 The term Laser stands for Light
Amplification by Stimulated Emission
of Radiation.
 Laser light is Monochromatic, which
means that it consists of a single color
and not a mixture of colors.
 Laser light is also called Coherent
light, which means a single
wavelength
Symbol:
Aplications: Laser diodes and are used in the
pick-up system of compact disk (CD)
players.
 Laser diodes are also used in laser
printers.
 Laser diodes are also used in fiber-
optic systems.
 Laser diodes are used for the
treatment of cancer.
 There are wide uses of laser in
The schottky diode
The Schottky Diode
 Schottky diodes are high-current diodes
used primarily in high-frequency and
fast-switching applications.
 They are also known as hot-carrier
diodes
 A Schottky diode is formed by joining a
doped semiconductor region (usually n-
type) with a metal such as gold, silver, or
platinum.
Symbol:
The PIN Diode
The PIN Diode:
 The pin diode consists of heavily doped
p and n regions separated by an intrinsic
region.
 When reverse-biased, the pin diode acts
like a nearly constant capacitance.
 When forward-biased, it acts like a
current-controlled variable resistance.
 The low forward resistance of the
intrinsic region decreases with increasing
current.
 Symbol:
The Tunnel Diode
The Tunnel Diode:
 The tunnel diode exhibits a special
characteristic known as negative
resistance.
 This feature makes it useful in oscillator
and microwave amplifier applications.
 Tunnel diodes are constructed with
germanium or gallium arsenide by
doping the p and n regions much more
heavily than in a conventional rectifier
diode. This heavy doping results in an
extremely narrow depletion region
Allah Hafiz

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types of diode

  • 3. Types of Diodes There are following major types of diodes.  The Zener Diode  The Varactor Diode  The Light-Emitting Diode  The Photodiode  The Laser Diode  The Schottky Diode  The PIN Diode  The Tunnel Diode
  • 5. Light-Emitting Diode (LED)  An LED emits light when forward- biased.  LEDs are available for either infrared or visible light.  High-intensity LEDs are used in large- screen displays , traffic lights, automotive lighting, and home lighting etc. Symbol:
  • 6. Explanation:  When the device is forward-biased, electrons cross the pn junction from the n-type material and recombine with holes in the p-type material.  The difference in energy between the electrons and the holes corresponds to the energy of visible light.  When recombination takes place, the recombining electrons release energy in the form of photons  The light output (both intensity and color) is also dependent on temperature. Light intensity goes down with higher temperature
  • 8. The Photo Diode:  The photodiode is a device that operates in reverse bias.  The photodiode exhibits an increase in reverse current with light intensity.  A diode in which the reverse current varies directly with the amount of light. Symbol
  • 9. Explanation:  The photodiode has a small transparent window that allows light to strike the pn junction.  when its pn junction is exposed to light, the reverse current increases with the light intensity. When there is no incident light the reverse current, is almost negligible and is called the dark current.  Some typical photodiodes are shown in Figure
  • 12. The Zener Diode:  A diode designed for limiting the voltage across its terminals in reverse bias.  A zener diode maintains a nearly constant voltage across its terminals over a specified range of zener currents.  The zener diode operates in reverse breakdown.
  • 13. Explanation:  A Zener diode is a silicon pn junction device that is designed for operation in the reverse-breakdown region. The breakdown voltage of a zener diode is set by carefully controlling the doping level during manufacture. when a diode reaches reverse breakdown, its voltage remains almost constant even though the current changes drastically, and this is the key to zener diode operation.
  • 14. Continue…  This volt-ampere characteristic is shown again in Figure with the normal operating region for zener diodes shown as a shaded area.
  • 16. The Varactor Diode:  A variable capacitance diode.  The capacitance of a varactor varies inversely with reverse-bias voltage  The current regulator diode keeps its forward current at a constant specified value. Symbol:
  • 17. Explanation:  A varactor is a diode that always operates in reverse bias and is doped to maximize the inherent capacitance of the depletion region. The depletion region acts as a capacitor dielectric because of its nonconductive characteristic. The p and n regions are conductive and act as the capacitor plates, as shown in figure:
  • 19. The Laser Diode:  The term Laser stands for Light Amplification by Stimulated Emission of Radiation.  Laser light is Monochromatic, which means that it consists of a single color and not a mixture of colors.  Laser light is also called Coherent light, which means a single wavelength Symbol:
  • 20. Aplications: Laser diodes and are used in the pick-up system of compact disk (CD) players.  Laser diodes are also used in laser printers.  Laser diodes are also used in fiber- optic systems.  Laser diodes are used for the treatment of cancer.  There are wide uses of laser in
  • 22. The Schottky Diode  Schottky diodes are high-current diodes used primarily in high-frequency and fast-switching applications.  They are also known as hot-carrier diodes  A Schottky diode is formed by joining a doped semiconductor region (usually n- type) with a metal such as gold, silver, or platinum. Symbol:
  • 24. The PIN Diode:  The pin diode consists of heavily doped p and n regions separated by an intrinsic region.  When reverse-biased, the pin diode acts like a nearly constant capacitance.  When forward-biased, it acts like a current-controlled variable resistance.  The low forward resistance of the intrinsic region decreases with increasing current.  Symbol:
  • 26. The Tunnel Diode:  The tunnel diode exhibits a special characteristic known as negative resistance.  This feature makes it useful in oscillator and microwave amplifier applications.  Tunnel diodes are constructed with germanium or gallium arsenide by doping the p and n regions much more heavily than in a conventional rectifier diode. This heavy doping results in an extremely narrow depletion region