If you continue browsing the site, you agree to the use of cookies on this website. e Its width depends upon the doping level.. thin depletion layer e Heavy doped o lightly doped thick depletion layer, POTENTIAL BARRIER The electrons in the N region have to climb the potential hill in order to reach the P region Electrons trying to cross from the N region to P region experience a retarding field of the battery and therefore repelled. Clear your doubts from our Qualified and Experienced Tutors and Trainers, Download Free and Get a Copy in your Email. Here discussion is limited only to acquaintation with the basic techniques and terminology (not expertise in fabrication). 1. ... PN JUNCTION DIODES AND. It operates like any other forward biased junction diode. Looks like you’ve clipped this slide to already. The LED is a special type of diode and they have similar electrical characteristics of a PN junction diode. o For each hole in the P section that combines with an electron from the N section, a covalent bond breaks and an electron is liberatyed which enters the positive terminal Thus creating an electron hole pair. pn-junction-fabrication In practice, the P-N junction is formed from a single mono crystalline structure by adding carefully controlled amounts of donor and acceptor impurities. ... PIN Diode Working Characteristics and Its Applications.pdf. PN junction diode – Study Material. This concentration will be more at the junction. PN junction can basically work in two modes, (Abattery is connected to the diode) forward bias mode (positive terminal connected to p-region and negative terminal connected to n region) reverse bias mode (negative terminal connected to p-region and positive terminal connected to n region) … For each approved PPT you will get 25 Credit Points and 25 Activity Score which will increase your profile visibility. Joining p-and n-doped semiconductors. A PN junction is the simplest form of the semiconductor diode. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage as the diode has an exponential current-voltage ( I-V ) relationship. It is used majorly in rectifier and voltage regulator circuits. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. They become minority carriers of the other side. Questions you should be able to answer by the end of today’s lecture: The LED occupies the s… Thus a pn junction is formed in diode. interface or a boundary between two semiconductor material types 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 N-regions. The circuit connection for determining the V-I characteristics of a pn junction is shown in the figure below. If one side of a single crystal of pure semiconductor (Ge or Si) is doped with acceptor impurity atoms and the other side is doped with donor impurity atoms, a PN junction is formed as shown in Fig P region has a high concentration of holes and N region contains a large number of electrons. It supplies a voltage and a current to a resistive load (light, battery, motor). A P-type material has holes as the majority carriers and an N-type material has electrons as the majority carriers. Holes. In LED, the p and n regions are forward biased. The overall unit is of very small dimension nearly about 2.5 mm. Volt-ampere (V-I) characteristics of a pn junction or semiconductor diode is the curve between voltage across the junction and the current through the circuit. Let us consider few notations. Movement of electrons and holes when forming the junction Depletion Region Approximation: Step Junction Solution Fig. P-N Junction Diode: A P-N Junction Diode is one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Similarly, o An additional holes from the P region are repelled by the net positive charge of the n region. o Potential thus produced are called ..potential barrier Ge..O.3V Si ..o.7V. 40 30 20 10 40 Forward Bias Region 140 V (volts) 120 80 0.4 2 6 0.8 12 V (volts) Reverse Bias Region Figure 5.1: Diode Characteristics. They are also called p-n diodes in analogy with vacuum diodes. Today: 1. P type and N type semiconductors, takenseparately are of very limited use.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. PN Junction Diode ENGI 242 ELEC 222 PN Junction Diode Diode Model Analysis Ideal Approximation Exact Diode Specification Sheets Diode Resistance Static Resistance RD ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 6e985b-NzNlY When the length of the nregion is longer than the di usion length, the hole concentration at a distance xfrom the depletion region, marked in gure 3, is given by p n(x) = p n(0) exp(x L h) excess holes ) p … Lecture 18 The P-N Junction (The Diode). Please enter the OTP sent to your mobile number: Post an enquiry and get instant responses from qualified and experienced tutors. In 1962, Nick Holonyak has come up with an idea of light emitting diode, and he was working for the general electric company. PN.ppt - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. Forward biasing a pn junction diode is very simple. Normally the voltage is taken along the x-axis and current along y-axis. PN Junction diode. Once the junction is crossed, a number of electrons and the holes will recombine . The P … 3. As only the junction is exposed to radiation, thus, the other portion of the glass material is painted black or is metallised. If a P-type and an N-type material are brought close to each other, both of them join to form a junction, as shown in the figure below. o The depletion layer contains no free and mobile charge carriers but only fixed and immobile ions. As the name stands PN junction Diode is made up of P type and N Type semiconductor material. o As an switch in computer circuits. P-N JUNCTION  Also known as a diode  One of the basics of semiconductor technology -  Created by placing n-type and p-type material in close contact  Diffusion - mobile charges (holes) in p- type combine with mobile charges (electrons) in n-type 14. Light Emitting Diode (LED) works only in forward bias condition. If you continue browsing the site, you agree to the use of cookies on this website. An attractive animation is presented in this video with complete voice description. Working of Light Emitting Diode. 1. Forward biased diode: In a very PN junction diode once the forward voltage is applied that is, a positive terminal of a source is connected to the p aspect, and conjointly the negative terminal of the availability is connected to the n-type aspect, the diode is speculated to be in forward biased condition. o As detectors in radios to detect audio signals o As LED to emit different colours. Formation of depletion layer the excess electrons in the N region cross the junction and combine with the excess holes in the P region. N region loses its electrons ......becomes + VIY charged P region accepts the electrons ......becomes -vly charged At one point , the migratory action is stopped. When a forward voltage is applied to the PN junction diode. You can change your ad preferences anytime. When free electrons reach the junction or depletion region, some of the free electrons recombine with the holes in the positive ions. Hence it is an unidirectional device. The m… ADVANTAGES: o No filament is necessary Occupies lesser space o Long life. V-I characteristics of p-n junction diode. Current-voltage characteristics of the p-n junction. Now, in this junction, there exist… o Thus the P N junction diode allows the electrons flow only when P is positive , o This property is used for the conversion of AC into DC , Which is called rectification. Forward biased PN junction o. PN junction diodes can be obtained in a number of semiconductor materials - the earliest diodes tended to be made from germanium, but most of them today are silicon diodes. o Electronic Symbol .....the triangle shows indicated the direction of current P type N type Depletion layer forms an insulator between the 2 sides. Clipping is a handy way to collect important slides you want to go back to later. 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