A special type of pn junction diode that operates in reverse biased condition, more specifically in breakdown region is known as zener diode. To understand how a pnjunction diode works, begin by imagining two separate bits of semiconductor, one ntype, the other ptype. A diode is also a tool that exclusively permits unidirectional flow of current if the diode is operated at a particular voltage level. Forward and reverse characteristics of a pn junction diode. Difference between schottky diode and pn junction diode. In pn junction diode, potential barrier is approximately 0. This lecture uncovers the basic science of semiconductor devices and solar cells, including pn junction and photovoltaic effects. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. A pn junction is a boundary or interface between two types of semiconductor materials, ptype. A lead is drawn at each end of the pn junction, and a plastic diode, glass or metal material is used as the package to form a crystal diode, as shown in the following figure.
Most of the times a resistance has to be connected in series with it to limit the electric current flowing through the diode. The basic difference between a forward bias and reverse bias is in the direction of. A single silicon atom consists of fourteen negatively charged electrons. Working of pn junction diode with biasing, characteristics. A pn junction consists of two semiconductor regions with opposite doping type as shown in figure. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode. According to the classical laws of physics, a charged particle sin order to cross an energy barrier should possess energy at least equal to the energy barrier. Light emitting diode led working, construction and symbol. 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. A semiconductor device oracle magazine pdf primer doping and diodes. This means that greater the intensity of light falling on the pn junction of photo diode, the greater will be the reverse current. Pn junction diode is a device made of two semiconductor material joined together with the required amount of impurity. 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.
A photodiode is a kind of light detector which involves conversion of light into voltage or current based on the mode of operation of the device. Tunnel diode working principle and characteristics ece. Pn junction diode is one of the fundamental elements in electronics. It is constructed of a p and an n junction connected together. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode, switching or tuner varactor diode. The junction is formed when these two materials connected together. This is the basic construction of the pn junction diode. Bias is the application of a voltage across a pn junction. Pn junction diode theory and current conduction mechanisms.
When a rectifier diode is reverse biased, it has a very small reverse leakage current. The reverse current in a photo diode is directly proportional to the intensity of light falling on its pn junction. When diode is reverse biased, majority carriers are blocked and only a small current flows through the diode due to the minority charge carriers. The led is a special type of diode and they have similar electrical characteristics of a pn junction diode. Light emitting diode led working, construction and. Varactor diode definition, symbol, construction and. Optocouplers working principle instrumentation tools. Jul 28, 2016 in pn junction diode, potential barrier is approximately 0. A pnjunction diode is formed when a ptype semiconductor is fused to an ntype semiconductor creating a potential barrier voltage across the diode junction. Pn junction diode and its characteristics in chapter 1 understanding the pn junction, we have seen how a pn junction is formed from a ptype and ntype semiconductor.
Home popular posts project ideas electrical electronics robotics technology download projects list. Semiconductor pnjunction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. The indispensable operation in semiconductor diode is the basis for understanding of all the semiconductor diodes. Construction and working of pn junction diode youtube. Ppt pn junction diode powerpoint presentation free to.
When carriers are injected across a forwardbiased junction, it emits incoherent light. The pn junction is the fundamental building block of the electronic age. Diode operation no current flows because the holes and electrons are moving in the wrong direction. Schottky diode working and applications authorstream. Throughout this methodology, free electrons which are from n aspect will spread into the p aspect and recombine with. To understand how a pn junction diode works, begin by imagining two separate bits of semiconductor, one ntype, the other ptype. By adding connections to each end of the ptype and the ntype materials we can produce a two terminal device called a pn junction diode which can be biased by an external voltage to either. Dec 11, 2017 diode seminar ppt and pdf report download. Pn junction diode is a diode which can be used as a rectifier, logic gate, voltage stabiliser, switching device, voltage dependent capacitor and in optoelectronics as a photodiode, lightemitting diode led, laser diode, photo detector, or solar cell in electronics. Two parallel lines at the cathode side represents two conductive plates and the space between these two parallel lines represents dielectric. The negative terminal of the battery is connected to the anode of a diode and positive terminal of battery is connected to cathode. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner work ings of the pn junction. From the above, it follows that zero power dissipation occurs in an ideal diode.
Aug 11, 2011 principles of solar cells, leds and diodes. Pn junction diode baising and its vi characteristics. Working of a pn junction current iv characteristic of reverse bias a pn junction diode. So, in this pn junction tutorial, we will discuss some of the basics of a pn junction, how a pn junction is formed, characteristics of pn junction and many other aspects. 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. A light emitting diode led is essentially a pn junction diode. Varactor diode definition, symbol, construction and working. Winner of the standing ovation award for best powerpoint templates from presentations magazine. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. The circuit symbol of pn junction diode is shown below. Diodes exclusively block current in the reverse direction whereas the reverse voltage is within a restricted vary and if not reverse barrier breaks and conjointly the. However, if we join or fuse these two semiconductor materials together they behave in a very different way merging together and producing what is generally. Diodes exclusively block current in the reverse direction whereas the reverse voltage is within a restricted vary and if not reverse barrier breaks and conjointly the voltage at that this breakdown happens is termed. Learn more about schottky diode working, construction, vi characteristics, features and applications authorstream presentation.
The working principle of a pn junction diode can be broadly understood under three categories. Tunnel diode working principle, characteristics and applications. Chart and diagram slides for powerpoint beautifully designed chart and diagram s for powerpoint with visually stunning graphics and animation effects. Since a junction forms between a p type and n type material it is called as pn junction. How a pnjunction diode works university of st andrews. Apr 05, 2019 in this tutorial, we will learn about pn junction diodes and in particular the characteristics and working of pn junction diode. Although it is not discussed majorly outside the concept of pn junction diode and sometimes the transistor, a pn junction is an essential topic in semiconductor electronics. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from.
Unbiased pn junction, forward biased pn junction and reversed biased pn junction. The most common colors of leds are orange, yellow, green and red. Pn junction diode and diode characteristics basic electronics. Understanding about the pn junction diode theory and working. This understanding will lay a better foundation for exploring further into different aspects of semiconductor electronics. The pn junction is a versatile element, which can be used as a. Pn junction diode and characteristics of pn junction diode.
This diode emits laser light when it is forward biased. The crystal diode is a pn junction formed by a ptype semiconductor and an ntype semiconductor, and a space charge layer is formed on both sides of the interface, and a selfbuilt electric field is built. In other words, we can say that the concentration of free electrons is high and that of holes is very low in an ntype semiconductor. We know that in the ntype semiconductor, a large number of free electrons are present. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect.
Pn junction theory a pn junction is formed when an ntype material is fused together with a ptype material creating a semiconductor diode in the previous tutorial we saw how to make an ntype semiconductor material by doping a silicon atom with small amounts of antimony and also how to make a ptype semiconductor material by doping another. Lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents. If we join a piece of p type material to a pieceof n type material such that the crystalstructure remains continuous at the boundary, a pn junction is formed 2. 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.
Such junctions show a pronounced rectifying behavior. The schematic symbol of led does not represent the color of light. Silicon a single silicon atom consists of fourteen negatively. Jan 29, 2019 pn junction diode is one of the fundamental elements in electronics. Most of the commercial leds are realized using a highly doped n and a p junction. Researchers working on solar cells and led devices, and. The diode always conducts in one direction of current flow and refuses to conduct in other direction. Our new crystalgraphics chart and diagram slides for powerpoint is a collection of over impressively designed datadriven chart and editable diagram s guaranteed to impress any audience.
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. The working principle of the pin diode exactly same as a normal diode. Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. 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.
Oct 09, 2018 the circuit symbol of pn junction diode is shown below. 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. The word diode can be explained as di means two and ode is obtained from electrode. The pn junction diode is the typical diode that has been used in the previous circuits. The behaviour of the pn junction with regards to the potential barriers width produces an asymmetrical conducting two terminal device, better known as the pn junction diode. Tunnel diode working principle, characteristics and. This is the voltage required to reach a flat band diagram and sets an upper limit typically an overestimate for the voltage that can be applied to a diode before it burns itself up. A pn junction diode is made by forming a ptype region of material directly next to a ntype region. How diode works, animation diode, animation pn junction, working of pn junction, how does a pn junction. The circuit symbol of the varactor diode is almost similar to the normal pn junction diode. 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, v is voltage applied across diode, v t is the voltage equivalent of temperature.
Pin diode working characteristics and its applications. Are specifically designed to operate under reverse breakdown conditions. If one side of a single crystal of pure semiconductor germanium ge or. Pn junction can basically work in two modes, a battery is connected to the diode oforward bias mode positive terminal connected to pregion and negative terminal connected to n region areverse bias mode negative terminal connected to pregion and positive terminal connected to n region. The pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. What is the forward current when the forward bias voltage is 0. The reverse current in a photodiode is directly proportional to the intensity of light falling on its pn junction. Because of this, a technique remarked as diffusion takes place. 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. These materials are ntype, having electrons are majority carrier and ptype material, having holes are majority carrier. Diode working principle and types of diode electrical. Diode circuits tutorial pdf 25p this note covers the following topics. In 1962, nick holonyak has come up with an idea of light emitting diode, and he was working for the general electric company. This article discusses about pn junction diode, diode theory of zero bias, forward bias, reverse bias with vi.
Pn junction tutorial introduction to pn junction diodes. We now consider a pn diode with an applied bias voltage, va. In this tutorial, we will learn about pn junction diodes and in particular the characteristics and working of pn junction diode. Nside will have an important variable of electrons and intensely few holes whereas the p aspect will have a more concentration of holes and intensely few electrons. A diodes working principle depends on the interaction of ntype and ptype semico nductors. Ive tried to make this explanation as simple as possible so that no conceptual doubts arise. In its basic form a semiconductor diode is formed by making pn junction which is one of the fundamental structures within semiconductor technology. We have also learned about diffusion current, depletion region. Before going to the working, i would like to explain. Pn junctions consist of two semiconductor regions of opposite type. A pn junction diode is a twoterminal electronics element, which can be classified as either step graded or linear graded. Hence the particle will cross the energy barrier if its energy is greater than the barrier and. Bring them together and join them to make one piece of semiconductor which is doped differently either side of the junction.
The pn junction diode photon emission and absorption the solar cell. The diode the diode is a two terminal semiconductor device that allows current to flow in only one direction. In the next tutorial about the pn junction, we will look at one of the most interesting applications of the pn junction is its use in circuits as a diode. Working principle of pn junction diode polytechnic hub.
The region on the left is ptype with an acceptor density na, while the region on the right is ntype with a. The pn junction is a building block for construction of diodes,transistors,amplifiers,integrated circuits etc. The light emitting diode is a twolead semiconductor light source. Pn junction diode in the reversebiased configuration is sensitive to light from a range between 400nm to nm, which includes visible light. Reverse voltage above 25 v destroys the junction permanentaly. Basic diode electronics introduction to diodes the pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. Before going to the working, i would like to explain how exactly the junction diode is made. They are also called pn diodes in analogy with vacuum diodes. 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. Researchers working on solar cells and led devices, and those in the electronics industry would also benefit from the background information the book provides.
This means that greater the intensity of light falling on the pn junction of photodiode, the greater will be the reverse current. Photodiodes their working principles and applications. The principle of operation will be explained using a gedanken experiment, an experiment, which is in principle possible but not necessarily executable in. Hence the particle will cross the energy barrier if its energy is greater than the barrier and cannot cross the barrier if its energy is less than the. 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. Lightemitting diodes circuit, working principle and application.
With proper biasing, pn diode allows current to flow in single direction. Pn junction operation in forwardbias mode, showing reducing depletion width. Definition, symbol, and types of diodes electrical4u. 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. These diodes have a very accurate and specific reverse breakdown voltage.
In the same way if the nside is connected to the positive terminal of the supply and the pside to the negative terminal of the supply, the diode is said to be reversed biased. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. P type and n type semiconductors, takenseparately are of very limited use. There is another type of breakdown named as avalanche breakdown generally seen in the normal diode which requires large amount of reverse voltage to break the junction. Also, it explains the phenomenon of shockleyqueisser limit. Principle, construction, working, characteristics, advantages, disadvantages and applications it is specifically fabricated pn junction diode. Jan 16, 2018 pn junction diode is a device made of two semiconductor material joined together with the required amount of impurity. Its working principle is when the diode is reverse biased, small leakage currents pass through the diode, when the reverse voltage is further increased the leakage current also. Typical iv static characteristics of a silicon pn junction diode. Pn junction diode construction working and uses electrical. Pn junction theory for semiconductor diodes basic electronics.