General introduction to fabrication techniques of a pn junction diode. When ptype semiconductor is suitably joined to ntpye semiconductor,thesuitably joined to ntpye semiconductor,the contact surface is calleed pn junction. It is one of the simplest semiconductor devices as it allows current to flow in only one direction. Image source forward biasing a pn junction diode is very simple. At the pn junction, electrons from the ntype semiconductor will be attracted to the holes in the ptype semiconductor. Working of pn junction this simple pn junction animation video clearly explains the topics pn junction semi conductor or diode, what is forward bias and reverse bias, what is diffusion current. A pn junction diode allows electric current when it is forward biased and blocks electric current when it is reverse biased. When the diode is forwardbiased, it can be used in led lighting applications. In pn junction diode, n is at right and p is at left. 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.
The name diode is derived from diode which means a device that has two electrodes. Najmabadi, ece65, winter 2012 high concentration of h on the p side holes diffuse towards the junction high concentration of. 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. To understand how a pn junction diode works, begin by imagining two separate bits of semiconductor, one ntype, the other ptype. 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. 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. Vi characteristics of pn junction diode in 3biasing modes. Diode current voltage iv characteristics semiconductor diode consists of a pn junction with two contacts attached to the p and n sides v p n 0 qv i i s exp 1 kt i s is usually a very small current, i s. When one side of an intrinsic semiconductor is doped with acceptor i. Microsoft powerpoint inc221 lecture2 diode pn junction. A pn junction with open terminals excluding minority carriers f.
A perfect diode is a device that only allows current to flow through it in one direction, i. You just need to take a battery whose values can be varied from o to v volts, connect its positive terminal to the pside of pn junction diode and then connect the negative terminal of battery to the nside of the pn junction diode. Diode current voltage iv characteristics semiconductor diode consists of a pn junction with two contacts attached to the p and n sides v p n 0 qv i i s exp 1 kt i s is usually a very small current, i. When a ptype semiconductor is suitably joined to ntype semiconductor, the contact surface in called pn junction. An attractive animation is presented in this video with complete voice description.
The contact surface between the layers of ptype and ntype semiconductor pieces plated together so as to form a pn junction is called the pn junction. Zener breakdown does not result in damage of diode. Reverse bias external battery makes the cathode more positive than the anode a tiny current flows opposite to the arrow in the symbol. Lecture 15 the pn junction diode i iv characteristics november 1, 2005 contents. 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 pn junction diode is the typical diode that has been used in the previous circuits. 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. Diode animation free download as powerpoint presentation. P type and n type semiconductors, takenseparately are of very limited use. The vi characteristics or voltagecurrent characteristics of the pn junction diode is shown in the below figure. Pnjunction diode characteristics forward bias external battery makes the anode more positive than the cathode current flows in the direction of the arrow in the symbol. Their values depend on the individual doping concentrations forward biasing the junction shrinks the depletion width and the barrier, allowing thermionic emission and higher current. Dec 26, 2016 an attractive animation is presented in this video with complete voice description. Junction diodes questions and answers electronics post. 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 pn junction biasing the pn junction the diode trouble shooting. Pn junction diode is integral for all electronic devices to operate, aggregating. Pn diodes forward bias, small signal model, bjts prof j. A pn junction is the simplest form of the semiconductor diode.
The pn junction has the very useful property that electrons are only able to flow in one direction. The animation below shows the formation of the e at the junction between n and ptype material. Such junctions show a pronounced rectifying behavior. The pn junction is the root for semiconductor diodes. The conversion of alternating current into direct current is known as rectification. 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. A free powerpoint ppt presentation displayed as a flash slide show on id. Pn junction diode characteristics forward bias external battery makes the anode more positive than the cathode current flows in the direction of the arrow in the symbol. It is the most essential and the basic building block of the electronic device. A pn junction diode is made by forming a ptype region of material directly next to a ntype region. Pn junctions consist of two semiconductor regions of opposite type.
To understand how a pnjunction diode works, begin by imagining two separate bits of semiconductor, one ntype, the other ptype. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. The horizontal line in the below figure represents the amount of voltage applied across the pn junction diode whereas the vertical line represents the amount of current flows in the pn junction diode. Ppt pn junction diode powerpoint presentation free to. What is pn junctionwhat is pn junction pnjunctionpn junction.
However the stage is set to see how the pn junction functions as a diode. Are specifically designed to operate under reverse breakdown conditions. 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. The pnjunction is the root for semiconductor diodes. The energy gap between the valence level and the conduction level is midway between that of insulators and conductors such as metals, and thermal energy causes. Drift pn junction diodes log in or register to post comments. Silicon a single silicon atom consists of fourteen negatively. Normally the voltage is taken along the xaxis and current along yaxis. Animation p n junction semiconductor works forward. 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. Working of pn junction diode with biasing, characteristics. The pn junction diode is the basic semiconductor diode format. Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 20 prof. In the animation below, most majority carriers which enter the depletion region.
However if the diodes terminals are shorted together, a few holes majority carriers in the ptype material with enough energy to overcome the potential barrier will move across the junction against this barrier potential. Voltampere vi characteristics of a pn junction or semiconductor diode is the curve between voltage across the junction and the current through the circuit. Pn junction diode baising and its vi characteristics. Semiconductor pnjunction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. Pn junctions ece 663 in summary a pn junction at equilibrium sees a depletion width and a builtin potential barrier. From the above, it follows that zero power dissipation occurs in an ideal diode. Forward bias current flows reverse bias no current flow. Pn junction diode engi 242 elec 222 pn junction diode diode model analysis ideal approximation exact diode specification sheets diode resistance static resistance rd. When a diode is connected in a zero bias condition, no external potential energy is applied to the pn junction. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. This is bc the metalsemiconductor junction at the terminals counteract and balance v 0. Why is silicon preferred over germanium in the manufacture of semiconductor devices. We know semiconductor devices like transistors and diodes are the basic. A diode is also a tool that exclusively permits unidirectional flow of current if the diode is operated at a particular voltage level.
Find materials for this course in the pages linked along the left. Otherwise, we would be able to draw energy from an isolated pn junction, which violates conservation of energy. Diode animation pn junction semiconductors free 30day. As a result, the holes and the electrons at the pn junction disappear, forming a layer called depletion layer.
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. Simplified physical structure construction on a cmos chip. Due to this characteristic, the diode finds number of applications as given below. This is the basic construction of the pn junction diode.
Smith context this lecture will discuss zdiode currents in forward and reverse bias 6. Pnjunction diode characteristics ppt documentation. The pn junction is the fundamental building block of the electronic age. In practice, the pn junction is formed from a single mono crystalline structure by adding carefully controlled amounts of donor and acceptor impurities.
Sep 09, 20 however the stage is set to see how the pn junction functions as a diode. Bring them together and join them to make one piece of semiconductor which is doped differently either side of the junction. This presentation is a very informative piece on pn junction diode an important part of electronics education. Najmabadi, ece65, winter 2012 high concentration of h on the p side holes diffuse towards the junction high concentration of e on the n side. How a pnjunction diode works university of st andrews. Here discussion is limited only to acquaintation with the basic techniques and terminology not expertise in fabrication. Since current is only due to drifting of electrons, there is a limit to the increase in current as well. Pn junction formation and how it works circuitstoday.
A k schematic symbol for a pn junction diode p n representative structure for a pn junction diode zener diodes. This video explains complete process of diode working i. If an external potential is applied to the terminals of pn junction, it will alter the potential between the p and nregions. Pn junction diode is the most fundamental and the simplest electronics device.
The pn junction diode is a twoterminal device, which is formed when one side of the pn junction diode is made with ptype and doped with the ntype material. Definition, symbol, and types of diodes electrical4u. Semiconductor, silicon, pn junction, forward bias, reverse bias, diode. Vi characteristics of pn junction diode electronics post. A diode is nothing more than a pn junctiona diode is nothing more than a pn junction.
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