Construction and working of pn junction diode youtube. Questions you should be able to answer by the end of todays lecture. Before going to varactor diode, lets first take a look at the capacitor. The pn junction diode is the basic semiconductor diode format. This potential difference can alter the flow of majority carriers, so that the pn junction can be used as an opportunity for the diffusion of. The pn junction is the fundamental building block of the electronic age. Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. The positive terminal of the battery is connected to the anode of a diode and negative terminal to the cathode when battery is not connected, there is a barrier potential of 0. Most of the commercial leds are realized using a highly doped n and a p junction. Depletion layer opposes only the the majority carrier not minority carrier. The diode current in a tunnel diode is same as that for normal pn junction diode which is given as i diode i do exp v.
In the positive half cycle, during the time interval 0 to t2, diode d will be forward biased and conduct, i. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. A semiconductor diode is a two terminal electronic component with a pn junction. The contact surface between the layers of ptype and ntype semiconductor pieces plated together so as. Apr 07, 20 when revrese voltage is increased beyond a value,called breakdown voltage,the reverse current increases sharply and the diode shows almost zero resistance.
In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage as the diode has an exponential currentvoltage iv relationship and therefore we can not described its operation by simply using an equation such as ohms law. Reverse voltage above 25 v destroys the junction permanentaly. A pn junction diode is a twoterminal electronics element, which can be classified as either step graded or linear graded. Lets get a voltmeter and ammeter and connect it to the forward biased circuit of pn junction diode. Pn junction diode and characteristics of pn junction diode. When the diode is forwardbiased, it can be used in led lighting applications. A light emitting diode led is essentially a pn junction diode. Thus a reverse biased pn junction does not conduct current. Pin diode working characteristics and its applications. Apr 23, 2018 semiconductor pn junction diode is the simplest semiconductor device.
A special type of pn junction diode that operates in reverse biased condition, more specifically in breakdown region is known as zener diode. Jan 04, 2020 a pn junction is the simplest form of the semiconductor diode. Pn junctions consist of two semiconductor regions of opposite type. Ive tried to make this explanation as simple as possible so that no conceptual doubts arise. Jan 16, 2018 the diode is in forward bias mode when the positive and negative terminals of a dc voltage source is connected to pside and nside of the diode respectively. Electronics tutorial about the pn junction diode and the vi characteristics of pn. Working of pn junction diode with biasing, characteristics. A pin diode is almost similar to a normal pn junction diode however the only variation is the presence of intrinsic region.
Varactor diode is a pn junction diode whose capacitance is varied by varying the reverse voltage. When diode is reverse biased, majority carriers are blocked and only a small current flows through the diode due to the minority charge carriers. Simplified physical structure construction on a cmos chip. Working of a pn junction current iv characteristic of reverse bias a pn junction diode. The pin diode is an alteration of the pn junction for particular applications.
This article discusses about pn junction diode, diode theory of zero bias, forward bias, reverse bias with vi characteristics and its applications. Due to this large power gets dissipated in the diode which may damage it permanently. When no any external potential is provided to the diode. A pn junction diode is a twoterminal electronics element, which can be classified as either. Jan 16, 2018 pn junction diode is a device made of two semiconductor material joined together with the required amount of impurity. Iv characteristics uwhenever an electron on the pside moves to the nside, it is replaced by an electron generated through one of the rg centers ohmic ohmic minority minority excess majority carriers alocal excess majority carriers alocal e e excess carriers move to the contact with a relaxation time. Zero bias no external voltage potential is applied to the pn junction diode. The circuit symbol of the varactor diode is almost similar to the normal pn junction diode. Mar 22, 2018 pn junction diode characteristics provide us the information about the habitual working of the diode. Bring them together and join them to make one piece of semiconductor which is doped differently either side of the junction. After the pn junction diode was developed in the year 1940s, the diode was first exercised as a highpower rectifier, lowfrequency during the year 1952. Varactor diode definition, symbol, construction and working. Apr 05, 2019 working of pn junction diode if an external potential is applied to the terminals of pn junction, it will alter the potential between the p and nregions.
The barrier increase reduces the majority carrier diffusion to a negligible level. The load resistance r l is connected to these terminals through a pn junction diode d. Varactor diode definition, symbol, construction and. Pn junction diode is one of the fundamental elements in electronics. The anode which is the positive terminal of a diode is represented with a and the cathode. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. Jul 28, 2016 in pn junction diode, potential barrier is approximately 0. The pn junction has the very useful property that electrons are only able to flow in one direction.
Light emitting diode led working, construction and. Pn junction diode characteristics and working elexfocus. This potential difference can alter the flow of majority carriers, so that the pn junction can be used as an opportunity for the diffusion of electrons and holes. Semiconductor pn junction diode is the simplest semiconductor device. The occurrence of an intrinsic layer can significantly increase the breakdown voltage for the application of high. Before going to the working, i would like to explain. Read more pn junction diode and its working principle. So the practical application of pn junction diode is rectification.
The types of diode are as follow1 zener diode 2 pn junction diode 3 tunnel diode 4 varractor diode 5 schottky diode 6 photo diode 7 pin diode 8 laser diode 9 avalanche diode 10 light emitting diode. This region is nothing but serves as the depletion region between p and n regions. Hence the change of forward and reverse biased states makes the diode work as a switch, the forward being on. There is a small voltage drop across the diode terminals when current flows through a diode. As a result it is almost impossible for any electrons or holes to cross the depletion zone and the diode current produced is virtually zero. Diode working principle and types of diode electrical. Oct 10, 2019 a pn junction diode is a twoterminal semiconductor device. The doping level of the zener diode is somewhat higher than the normal pn junction diode so that it can provide a sharp breakdown voltage. When carriers are injected across a forwardbiased junction, it emits incoherent light. If you continue browsing the site, you agree to the use of cookies on this website. V t1 where i do is reverse saturation current and will be very high in tunnel diode compared to pn junction diode due to high doping concentrations. Such junctions show a pronounced rectifying behavior.
Understanding about the pn junction diode theory and working. The name diode is derived from diode which means a device that has two electrodes. Diode working principle and types of diode electrical4u. What happens when we join ptype and ntype semiconductors.
Doping with acceptor creates p type semiconductor while doping with donors produces n type. A pn junction is the simplest form of the semiconductor diode. Its made up from a small piece of semiconductor material usually silicon, it allows the electric current to flow in one direction while opposes the current in other direction. Pn junction diode baising and its vi characteristics. The word diode can be explained as di means two and ode is obtained from electrode. Diode is a two terminal pn junction that can be used in various applications. Pn junction diode, characteristics and applications 2020. Schottky diode working principle engineering tutorial. Here, the characteristics is the graph where the voltage is plotted on the xaxis and the current on the yaxis. They are also called pn diodes in analogy with vacuum diodes. The indispensable operation in semiconductor diode is the basis for understanding of all the semiconductor diodes. Reverse bias of pn junction when the voltage is applied this way round it tends to pull the free electrons and holes apart, and increases the height of the energy barrier between the two sides of the diode. Forming a pn junction doping one side of a piece of silicon with boron a ptype dopant and the other side with phosphorus an ntype dopant forms a pn junction.
This is the basic construction of the pn junction diode. Junction coming to the equilibrium by balancing the fermi level ef ef the balance is achieved by electrons diffusing into a pside bringing an extra negative charge in there and by the holes diffusing into an nside bringing an extra negative charge in there pn. Electronic circuits diode as a switch tutorialspoint. Definition, symbol, and types of diodes electrical4u. A simple circuit diagram is shown below, which has a pn junction diode, a battery in picture it is not shown as variable. Tunnel diode working principle and characteristics ece. Zener diode, its working, zener breakdown and its applications. A pn junction with open terminals excluding minority carriers f.
Najmabadi, ece65, winter 2012 high concentration of h on the p side holes diffuse towards the junction high concentration of. Pn junction diode construction working and uses electrical. A pn junction diode is formed when a ptype semiconductor is fused to an ntype semiconductor creating a potential barrier voltage across the diode junction the effect described in the previous tutorial is achieved without any external voltage being applied to the actual pn junction resulting in the junction being in a state of equilibrium. The working principle of the pin diode exactly same as a normal diode. Working of pn junction diode if an external potential is applied to the terminals of pn junction, it will alter the potential between the p and nregions. If one side of a single crystal of pure semiconductor germanium ge or. A pn junction diode is one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. Working principle of pn junction diode polytechnic hub. These materials are ntype, having electrons are majority carrier and ptype material, having holes are majority carrier. It is used for many forms of rectification for current levels both large and small, as well as high and low voltage levels, and it finds many uses in all manner of electronic circuits. The symbol of led is similar to the normal pn junction diode except that it contains arrows pointing away from the diode indicating that light is being emitted by the diode.
And the working of this pn junction diode under forward and reverse bias has been explained. Pn junction diode plays a vital role in our electronic fields, because of their unique property current flows in only one direction they are used in many electronic or electrical circuits like rectifiers, switches, clippers, clampers, voltage multipliers in this article, we will learn about what is a pn junction diode and how it works and also effect on pn junction diode with different. After having known about various components, let us focus on another important component in the field of electronics, known as a diode. Silicon a single silicon atom consists of fourteen negatively. Application of the minority carrier diffusion equation. A pnjunction diode is formed when a ptype semiconductor is fused to an ntype semiconductor creating a potential barrier voltage across the diode junction the effect described in the previous tutorial is achieved without any external voltage being applied to the actual pn junction resulting in the junction being in a state of equilibrium. When revrese voltage is increased beyond a value,called breakdown voltage,the reverse current increases sharply and the diode shows almost zero resistance. The potential at terminal x with respect to y will vary as a sine function with time. This increases the potential at the pside and decreases the potential at the nside of the diode. In ideal conditions, this pn junction behaves as a short circuit when it is forward biased, and as an open circuit when it is in the reverse biased. The diode is in forward bias mode when the positive and negative terminals of a dc voltage source is connected to pside and nside of the diode respectively. In any pn junction diode, the p region contains holes as it has been doped to make sure that it has a majority of holes.
The negative terminal of the battery is connected to the anode of a diode and positive terminal of battery is connected to cathode. Jan 29, 2019 pn junction diode is one of the fundamental elements in electronics. Two parallel lines at the cathode side represents two conductive plates and the space between these two parallel lines represents dielectric. In this video, the pn junction diode has been explained. Light emitting diode led working, construction and symbol. Lecture 11 pn junction diodes doolittle georgia tech. Oct 09, 2018 a pn junction diode is a two terminal single crystal semiconductor device whose one side is doped with acceptors and other side by donors. Pn junction diode characteristics provide us the information about the habitual working of the diode. Pn junction diode in the reversebiased configuration is sensitive to light from a range between 400nm to nm, which includes visible light. Pn junction diode is a device made of two semiconductor material joined together with the required amount of impurity. Depletion region created across the pn junction by the initial movement of majority carrier across the junction. With proper biasing, pn diode allows current to flow in single direction. Junction coming to the equilibrium by balancing the fermi level ef ef the balance is achieved by electrons diffusing into a pside bringing an extra negative charge in there and by the holes diffusing into. A pn junction diode is formed by doping one side of a piece of silicon with a ptype dopant boran and the other side with a ntype dopant phosphorus.
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