Junction transistor, transistor current components, transistor as an amplifier, c b and c e. A pn junction diode is a twoterminal electronics element, which can be classified as either. Lecture 7 large and small signal modelling of pn junction diodes. A current far in excess of that predicted by the ideal theory exists at small. Pn junction tutorial introduction to pn junction diodes.
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 electrons diffuse towards the junction n side is positively charged because it has lost electrons. Quantitative theory of pn junction diode electrical. The pn junction solidstate device theory electronics. 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. Najmabadi, ece65, winter 2012 high concentration of h on the p side holes diffuse towards the junction high concentration of.
Gupta assistant professor department of electronics engineering shri ramdeobaba college of engineering and management, nagpur. Pnjunction diode characteristics ppt documentation. Quantitative theory of pn diode currents brainkart. Introduction to semiconductors and the pn junction diode robert clancy 04329741 april 10, 2006 abstract in this experiment the iv characteristicof the pn junction diode is determined andthe applicationofthe diodeasarecti. The pn junction is a versatile element, which can be used as a. Pn junctions consist of two semiconductor regions of opposite type. Zero bias no external voltage is applied to the pn junction diode. 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. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. Forward bias current flows reverse bias no current flow. Numerical analysis of semiconductor pn junctions using matlabtm.
Diode theory diode as a conductor when a voltage is applied current will flow. Quantitative analysis of the pn junction we now have all the tools we need to derive the diode equation properly and to see how the material properties come into play. The shift of electrons from n side of the pn junction to holes annihilated on the p side of the pn junction produces a potential barrier voltage. Dec 27, 2017 the symbolic representation of the diode is as follows. Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 20 prof. 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. Determine minority carrier currents from continuity equation.
Lecture 5lecture 5 pn junction diodes quantitative. A pn junction with open terminals excluding minority carriers f. When the ntype semiconductor and ptype semiconductor materials are first joined together a very large density gradient exists between both sides of the pn junction. Quantitative treatment of the pn junction in equilibrium. The primary difference between silicon and germanium diodes is the voltage needed for the diode to turn on. Theory of pn junction diode, diode current equation youtube. Semiconductor, silicon, pn junction, forward bias, reverse bias, diode. I o we can recast the expression for i o in terms of doping densities by noting that n p n i 2n a andp n n i 2n d. Semiconductor pn junction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. Jan 29, 2019 pn junction diode is one of the fundamental elements in electronics. A simple circuit diagram is shown below, which has a pn junction diode, a battery in picture it is not shown as variable. Pn diodes forward bias, small signal model, bjts prof j. Iv characteristics pn junction diode reverse biasing a pn junction when the polarity of the battery is reversed, the cathode is connected to positive end of the battery and anode to negative.
Lets get a voltmeter and ammeter and connect it to the forward biased circuit of pn junction diode. 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. Review, pn junctions, fermi levels, forward bias prof j. The pn junction is the root for semiconductor diodes. Pdf numerical analysis of semiconductor pn junctions using. The recombination at the junction allows battery current to flow through the pn junction diode. 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. I o is the saturation current, so called because at sufficiently large reverse bias v 3kt, say i.
P n junction theory behind p n junction electrical4u. Such junctions show a pronounced rectifying behavior. May 16, 2015 for the love of physics walter lewin may 16, 2011 duration. The symbolic representation of the diode is as follows. Image source forward biasing a pn junction diode is very simple. A pnjunction is formed when an ntype material is fused together with a ptype material creating a semiconductor diode. Simplified physical structure construction on a cmos chip. Vi characteristics of pn junction diode in 3biasing modes. 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 silicon atom with boron. We begin by considering the forward biased arrangement in which the barrier height. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. Silicon a single silicon atom consists of fourteen negatively.
We can form a p n junction practically by doping one side of a semiconductor crystal by trivalent impurity and another side by pentavalent impurity. 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. A pn junction is formed when an ntype material is fused together with a ptype material creating a semiconductor diode. It is the most essential and the basic building block of the electronic device. Apr 29, 2020 quantitative theory of pn junction diode electrical engineering ee notes edurev is made by best teachers of electrical engineering ee. Pn junction theory for semiconductor diodes electronicstutorials. Lecture 5 5 pn junction diodes quantitative analysis doolittle. Theory of pn junction diode, diode current equation. Working of pn junction diode with biasing, characteristics. 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 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. P type and n type semiconductors, takenseparately are of very limited use.
Solve minority carrier diffusion equation in quasineutral regions. For the love of physics walter lewin may 16, 2011 duration. We can create a pn junction by connecting face to face one ptype sand one ntype semiconductor crystal block by special techniques. The pn junction biasing the pn junction the diode trouble shooting. When the diode is forwardbiased, it can be used in led lighting applications. Lecture 5lecture 5 pn junction diodes quantitative analysis. Diode in a circuit acts to clamp voltages i r ohms v 1 ir r ohms v v9v, 5v, 2v, 9v a i e kt where i o pa qv o i a 1 1 0.
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. Junction conductance kt qi g d d ece 315 spring 2006 farhan rana cornell university small signal model of a pn junction diode. You can download free quantitative theory of pn junction diode electrical engineering ee notes edurev pdf from edurev by using search. Also, it explains the phenomenon of shockleyqueisser limit. 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. 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. Diode pn junction when p and n type silicon are brought together during manufacture, a junction is created where the p type and n type materials meet, and holes close to the junction in the p type silicon are attracted into negatively charged n type material at the other side of the junction.
Lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents. Junction transistor, transistor current components, transistor as. This pn junction can be used to operate and implement the functions of a diode because it can conduct considerable current in the forward direction and roughly no current in the reverse direction. The pn junction diode is the basic semiconductor diode format. This lecture uncovers the basic science of semiconductor devices and solar cells, including pn junction and photovoltaic effects.
The arrow indicates the flow of current through it when the diode is in forward biased mode, the dash or the block at the tip of the arrow indicates the blockage of current from the opposite direction. Theory a semiconductor pn junction diode is a two terminal electronic device that allows current in only one direction. Semiconductor pnjunction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. Quantitative pn junction current lets start examining the different areas of the pn diode start in the quasineutral regions. Semiconductor physics semiconductors and diodessemiconductors. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. Silicon and germanium are two chemical elements called metalloids. This causes the holes to move toward the depletion region and the free electrons to move toward the depletion region. Note to those familiar with a diode turn on voltage. The diode is firmed by doping a semiconductor like silicon or germanium with trivalent impurity e.
Quantitative theory of pn junction diode electrical engineering. Pl5fcg6tovhr7p31bjvzsbg6jxuxv7fgaz unit 1 evaluation of electronics introduction to electronics. From the above, it follows that zero power dissipation occurs in an ideal diode. It is one of the simplest semiconductor devices as it allows current to flow in only one direction. We have the minority carrier diffusion equations but we know the electric field in the quasineutral regions is very small and this has consequences ece 340 lecture 24 101711. Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 19 prof. Pn junction diode is one of the fundamental elements in electronics. Ipn depends on applied voltage or injected concentration is a function of voltage. 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. Introduction to semiconductors and the pn junction diode.
Lecture 7 large and small signal modelling of pn junction. Draw the energy level diagram of a pn junction and explain how a junction barrier is developed across an unbiased junction. 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. Pn junction diode baising and its vi characteristics. This document is highly rated by electrical engineering ee students and has been viewed 1949 times. They are also called pn diodes in analogy with vacuum diodes. Pn junction diodes quantitative analysis math, math and more math georgia tech ece 4833. In this lecture, the educator has discussed how to derive a diode current equation in forward bias and reverse bias. And based on the applied voltage, there are three possible biasing conditions for the pn junction diode, which are as follows. The pn junction is the fundamental building block of the electronic age. Smith context this lecture will discuss zdiode currents in forward and reverse bias 6.
The valence band and conduction band in ntype material are slightly lower than that of ptype material. Pn junction diode and characteristics of pn junction diode. Both silicon and germanium can be combined with other elements called dopants to create solidstate electronic devices, such as diodes, transistors and photoelectric cells. The pnjunction is the root for semiconductor diodes. We have seen how a diode is made with p and n semiconductors but. This is the basic construction of the pn junction diode. Diode current equation diode equation thermal voltage and ideality factor diode duration. The depletion region shrinks allowing current to flow. Characteristics of junction diodes technical articles. This causes electrons from nregion to get attracted to positive terminal of the battery and holes by the negative terminal. One of the most common applications of the diode is the pn junction.
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