Tunnel diode: its construction and working, Physics

Assignment Help:

A tunnel diode is a highly conductively two terminal P-N junction doped heavily about 1000 layer width is a high conductively two terminal conventional diode. Because of heavy doping depletion layer width is reduced to an externally small value of the order of 10-5mm reverse breakdown voltage is also reduced to a very small value of the order resulting in appearance to the diode to be broken for any reverse voltage, and a negative resistance section is produced in volt ampere CHARACTISTICS of the diode. It is that the reduced depletion layer can form result in carriers “punching through” the junction with the velocity of light even when they do not possess enough energy to overcome the potential barrier. The result is that large forward current is produced at relatively low forward voltage (less than 100mv) such a mechanism of conduction in which charge carriers (possessing very little energy) punch through a barrier directly instead of climbing over it is called tunnelling. That’s why such diodes are known as tunnel diodes. Because of heavy doping the tunnel diode can conduct in reverse as well as in formed direction but it is usually used in forward biased mode.

CONSTRUCTION OF TUNNEL DIODES: Tunnel diodes are usually fabricated from germanium, gallium arsenide or gallium antimonite. Silicon is not used in the construction of the tunnel diodes because the ratio of peak value of forward current to the value of valley current is maximum in the case of gallium arsenide (approximately 15) and comparatively smaller for germanium (roughly 8) but very in case of silicon (about 3). Tunnel diodes are ordinary manufactured by allowing from gallium arsenide. The source materials are highly doped semiconductor crystal with an impurity concentration of the order of 1025 per cubic meter or more. It is noted that the tunnel diode being a low power device, can be easily damaged by heat and static electrically.

WORKING OF THE TUNNEL DIODES: Tunnel diodes exploit a strange quantum phenomenon called resonant tunnelling to provide interesting forward bias charactistics. When a small forward bias voltage is applied across a tunnel diode, it begins to conduct current. As the voltage is raised, the current increases and attains a peak value known as peak current. If the current is increased a little more, the current actually begins to decreases until it reaches a low point called the valley current. If the voltage is increased further yet, the current begins to increase again, the time without decreasing into another “valley”. The region on the graph where the current is decreasing while applied voltage is increasing is known as the region of the negative resistance.

 


Related Discussions:- Tunnel diode: its construction and working

Determine the electric field at the same point in sapce, Why it is in gener...

Why it is in general considered easier to determine the electric potential at a given point in space or at a given set of points in space due to a continuous charge distribution th

Universal Gravity, There is a point between the Earth and the Moon where th...

There is a point between the Earth and the Moon where the gravitational effects of the two bodies balance each other. Calculate the distance from the center of the Earth to this po

Filter, what is resistor filter?

what is resistor filter?

Mass defect of an atom, The decrease of mass is related to the binding of t...

The decrease of mass is related to the binding of the individual particles together inside the nucleus. Therefore every stable nucleus has a mass which is less than the total ma

Why do you not collapse in the pressure, Q. Why do you not collapse in the ...

Q. Why do you not collapse in the pressure created by the atmosphere? Answer:- If the outward pressure inside your body weren't equal to the pressure pressing in on you an

Point out the direction of the current, Point out the direction of the curr...

Point out the direction of the current if any induced to flow in the coil by the changing magnetic field. (Depicted is a view of the coil from the side. Toward the top of the displ

What takes place when you travel across the dateline, Q. What takes place w...

Q. What takes place when you travel across the dateline? Answer:- If westbound the day modify to the next day. If eastbound the day is the day prior to. Appears strange bu

Electrons are emitted from a photosensitive surface, Electrons are emitted ...

Electrons are emitted from a photosensitive surface when it is illuminated by green light but electron emission does not take place by yellow light. Will the electrons be emitted w

How lots cph is able keep the spin of photon, As we know photon's spin is o...

As we know photon's spin is one, how lots CPH (that have spin) is able keep the spin of photon? Answer; the photon spin like electron spin comes up of its properties and indepe

anant kumar

1/26/2013 4:37:02 AM

Write your message here..what is tunneling effect?explain working and characteristic of a tunnel diode.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd