pn junction diode working

The diode is forward biased. If the reverse current exceeds this maximum rating, the diode will get damaged. interface or a boundary between two semiconductor material types Zener effect is operated at. Thus we get output across-load i.e. It is used to convert AC to DC. How it occurs ? When the p-n junction is forward biased, the built-in electric field at the p-n junction and the applied electric field are in opposite directions. Zero bias: There is no external voltage applied to the p-n junction diode. To get an answer to all these questions, lets first try to understand the characteristics of a PN junction. The pn junction will perform satisfactorily if it is operated within the following limiting values or conditions: Your email address will not be published. What remains is the drift due to electric field. (I am familiar with the increase/decrease of potential of depletion barrier and agree with the books), I am very confused with this question. I hope you understood. for eachelectron hole combination that take place near the junction a covalent bond breaks in the p section near the +ve pole of the battery how it is formed? P-N Junction Diode. Our webiste has thousands of circuits, projects and other information you that will find interesting. so please help me. So the electrons in n-side gets pushed towards the junction (by force of repulsion) and the holes in p-side gets pushed towards the junction. DESC: Diode forward biased 24VDC Let us consider a thin p-type silicon semiconductor sheet. I am clearly understood to read it……. As we know, there is a difference in the concentration of holes and electrons at the two sides of a junction, the holes from the p-side diffuse to the n-side and the electrons from the n-side diffuse to the p-side. When we apply voltage to the terminals of diode, the width of depletion region slowly starts decreasing. We know a diode has a depletion region with a fixed barrier potential. So the net “diffusion current” is zero! From the analysis of both forward bias and reverse bias, we can arrive at one fact – a pn junction diode conducts current only in one direction – i.e during forward bias. Required fields are marked *, Frequently Asked Questions on p-n Junction. In forward bias condition external electric field ( produced by battery) will be opposite to the internal electric field ( produced depletion barrier ). When the two fields are added, the resultant electric field is in the same direction as the built-in electric field creating a more resistive, thicker depletion region. veryyyy goood explanation, i got it perfectly, please tell me about bridge wave rectifier, we connect 4 diodes in bridge but when the d1 and d2 are forward biased then haw the d3 and d4 are reversr biased, @Nayan – Read this article:- https://www.circuitstoday.com/full-wave-bridge-rectifier. Voltage is taken along the x-axis while the current is taken along the y-axis. The circuit connection for determining the V-I characteristics of a pn junction is shown in the figure below. I really appreciate. The p-n junction diode has two terminals called electrodes, one each from p-region and n-region. PN junction diode is the most common type of diode that’s used till date in Electronic circuits. Utmost/extremly thanks ….. QTY: 20pcs, DESC: Diode Reverse biased 24VDC 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. This drift is caused by the electric field generated by depletion region. It conducts current linearly with increase in voltage applied across the 2 terminals (provided the applied voltage crosses barrier potential). Semiconductor PN Junction Diode is the simplest semiconductor device. In a Silicon diode, the “barrier width” is higher than a Germanium diode. Here, we see that the direction of drift current is opposite to that of the diffusion current. Finally we will get a graph as shown. This results in movement of charge carriers (electrons and holes) from region of higher concentration to region of lower concentration. Similarly, when a hole goes from the p-side to the n-side, and ionized acceptor is left behind in the p-side, resulting in the formation of a layer of negative charges in the p-side of the junction. In that case, 1 volt will be dropped across the wires with the help of a very large current. Theoretically, internal resistance of a diode at breakdown is zero. In chapter 1 – Understanding the PN junction , we have seen how a PN junction is formed from a p-type and n-type semiconductor. When the diode is forward-biased, it can be used in LED lighting applications. Press Esc to cancel. Here, the characteristics is the graph where the voltage is plotted on the X-Axis and the Current on the Y-Axis. Photocurrents are produced due to generation of electron-hole pairs. So these are our questions. At break down, what happens really is that the diode gets damaged. diode worked on ac voltage but it will give output is DC why because ac has two half cycles in that case,it will conduct only positive half cycle….do not allow -ve cycles…, The junction information is clearly understand so nice of it thanx. Dynamic resistance of a diode is defined as the ratio of change in voltage to the change in current. If you could clarify that for me I would be glad. admin 09/01/2021 10 0. Last updated 12/2020 English English [Auto] Add to cart. A PN junction is the simplest form of the semiconductor diode. 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. 230 total views, 4 views today. It is also called as simply P-N junction or semiconductor diode. Learning anything is really fun when we question it. Its in conversion of alternating current to direct current (AC to DC). I think I missed something. As we know, if we use different semiconductor materials to make a p-n junction, there will be a grain boundary that would inhibit the movement of electrons from one side to the other by scattering the electrons and holes and thus, we use the process of doping. thanx ! This is another interesting factor, to explain. Even for a small change in applied voltage, there is a high increase in net current through the diode. You just need to take a battery whose values can be varied from (o to V volts), connect its positive terminal to the p-side of pn junction diode and then connect the negative terminal of battery to the n-side of the pn junction diode. when we talk about reverse bias ,thn the width of depletion layer increases thn after more reverse voltage(greater than reverse breakdown voltage) how current flow through dide? This region of positive charge and negative charge on either side of the junction is termed as the depletion region. explain the working of PN junction diode in forward and reverse biasing configuration please ? So that’s the forward bias characteristics of a pn junction diode. Working of a Photodiode. i hve a question. When the p-type is connected to the negative terminal of the battery and the n-type is connected to the positive side then the p-n junction is said to be reverse biased. Circuit for p-n junction diode as half-wave rectifier is given below: During the positive half cycle: The p-n junction is forward biased i.e the forward current flows from p to n, the diode offers a low resistance path to the current. Similarly holes from p-side gets pushed towards the n-side junction. A reverse biased pn junction diode acts like an open switch and blocks the flow of current from anode to cathode. Working of PN Diode Junction:. Forward biasing a pn junction diode is very simple. This results in a less resistive and thinner depletion region. It loses its junction & characteristics associated with the junction. This depletion region has a predefined width, say W. This width will vary for a Silicon diode and a Germanium diode. V-I Characteristics stands for voltage and current. yes, its very great answer that i want. We connected p-side of diode to negative terminal of battery and n-side of diode to positive terminal of battery. So “barrier potential” of a Silicon diode is higher than Germanium diode. The direction of external voltage applied in reverse bias is opposite to that of  external voltage applied in forward bias. This results in the concentration gradient between both sides of the terminals. The “diode” almost behaves like a shorted wire & hence current flows through it easily. The holes and electrons tend to move away from the junction. We know a pn junction has a “barrier potential”. So the practical application of pn junction diode is rectification! These materials are N-type, having electrons are majority carrier and P-type material, having holes are majority carrier. The positive side of a diode is known as the anode and the negative side is known as the cathode.. Current can spill out of the anode end to the cathode, but it cannot pass from cathode to the anode. Now this is what we call “characteristics of a pn junction diode” or the “behavior of diode under forward bias”. PN junction diode is one of the fundamental elements in electronics. As High Voltage Rectifier– The large width of the intrinsic layer allows the ability to the diode to tolerate high reverse voltage without the breakdown of the diode. From this data what you can infer ? Application of PIN diode. The two breakdown mechanisms are Zener breakdown and Avalanche breakdown. So here we connect positive terminal of battery to n-side of the diode and negative terminal of the battery to p-side of the diode. If you find these terms foreign, just read the chapter about “understanding the pn junction” once more. Here the interesting thing to note is that, diode does not conduct with change in applied voltage. The positive terminal of the battery is connected to the anode of a diode and negative terminal to the cathode. Its from the “characteristics graph” we have just drawn, we are going to make conclusions about the behavior of pn junction diode. There is a movement of electrons to the p-type material and movement of holes to the n-type material. Reverse bias: The negative terminal of the voltage potential is connected to the p-type and the positive is connected to the n-type. When the PN junction diode is under forward bias condition, the p-type is connected to the positive terminal while the n-type is connected to the negative terminal of the external voltage. This device is a combination of P-type and N-type semiconductor material hence it is also known as PN Junction Diode. Reverse saturation current flows in the beginning as minority carriers are present in the junction.Â, When the applied voltage is increased, the minority charges will have increased kinetic energy which affects the majority charges. If you have done upto this, the forward bias circuit of pn junction diode is complete. As the applied voltage increases from 0 volts to 0.7 volts, the depletion region width reduces from ‘W’ to zero. The movement of charge carriers inside the pn junction is the reason behind the current flow in the circuit. Your email address will not be published. To apply an external voltage, we usually connect 2 metallic contacts at the two ends of the pn junction ( known as terminals ); one on the p-side and other on the n-side. Keep keeping. The processes that follow after the formation of a p-n junction are of two types – diffusion and drift. A similar concentration gradient develops between the number of holes at the n-side junction region and the number of holes at region near the n-side terminal. Normally the voltage is taken along the x-axis and current along y-axis. Type above and press Enter to search. The barrier potential of silicon diode is 0.7 volts  What else ? We can determine the current-voltage characteristics. Forward bias of PN junction diode. 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.. Thanks Admin. Forward bias: The positive terminal of the voltage potential is connected to the p-type while the negative terminal is connected to the n-type. This means that greater the intensity of light on the PN junction of a Photo-diode, the greater will be the reverse current in the Photodiode. The basic difference between a forward bias and reverse bias is in the direction of applying external voltage. The P-N junction diode is a two-terminal device. Connect voltmeter, ammeter, vary the battery voltage, note the readings etc etc. A junction is formed between the P-type and N-type layers. Depletion region created across the pn junction by the initial movement of majority carrier across the junction. The more the light falls on the PN junction the more reverse current it produces. To conclude about pn junction characteristics, we need to get an answer to the first question we have raised – What is the use of pn junction? As I see it, we just consider 0.7V as a practival value for a conducting diode, where any variation of the current will cause a small variation on Vd, keeping it around the same 0.7V. We will understand the process of doping with the help of this example. Story behind Invention & Discovery of PN Junction, Magneto Resistor – Symbol, Working, Types & Characteristics, Carbon Film Resistor – Working, Construction & Applications, Photoresistor – Symbol, Working, Types & Applications, https://www.circuitstoday.com/full-wave-bridge-rectifier. Due to this movement, there is a formation of the depletion region. I have never seen a website this successful in explanation! There are two ways in which we can bias a pn junction diode. PN Junction diode is a device made of two semiconductor material joined together with the required amount of impurity. Your email address will not be published. The p-side has … In this article, we learn about PN junction diode characteristics in detail – like how to bias a PN junction (Forward & Reverse bias methods), behavior of PN junction during forward & reverse bias setups, how to plot the VI characteristics, what is reverse breakdown and many other essential concepts regarding a PN junction diode. In chapter 1, we have seen that  net current inside a pn junction is zero. Leave a Reply Cancel reply. Now there arises a concentration gradient between the number of electrons at the p-side junction region and the number of electrons at the region towards the p-side terminal. The PN junction diode is the basic semiconductor diode format. ?;). Thanks the author. Once the potential barrier is overcome by the diode, the diode behaves normal and the curve rises sharply as the external voltage increases and the curve so obtained is linear. Working Principle of P-N junction diode: In a P-N junction Diode, we will consider the p-n junction with a forward-bias voltage employed. For this crystal clear explanation….. Thanks. 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