We shall also derive an equation for the currentvoltage characteristic. Semiconductor pn junction diode is the simplest semiconductor device. 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. Introduction, formation of pn junction, diffusion diffusion current, depletion region,barrier potential. Develop an understanding of the pn junction diode and its behavior. A pn junction is a boundary or interface between two types of semiconductor materials, ptype and ntype, inside a single crystal of semiconductor. Diode is an electronic component that allows the flow of electricity in one direction without resistance or with very little resistance while in the opposite direction has. A p n junction diode meant to operate in the break down region is called a zener diode. One terminal of pn junction diode is anode and other is cathode. The voltampere or vi characteristics of a pn junction diode is basically the curve between voltage across the junction and the circuit current.
P n junction diode in the reversebiased configuration is sensitive to light from a range between 400nm to nm, which includes visible light. We also explained how depletion region is created, what barrier potential is and what diffusion. The term junction implies the boundary or region of transition between n type and p type semiconductor material. P n junction diode a pn junction is known as semiconductor diode. They are also called pn diodes in analogy with vacuum diodes. Image source forward biasing a pn junction diode is very simple.
This lecture uncovers the basic science of semiconductor devices and solar cells, including pn junction and photovoltaic effects. The name diode is derived from diode which means a device that has two electrodes. Schematic symbol for a pn junction diode p n representative structure for a pn junction diode zener diodes. In this physics digital electronics video lecture in hindi for class 12 we explained forward and reverse bias in pn junction diode in terms of.
Most introductory textbooks will tell you that a silicon pn junction drops 0. Given a semiconductor pn junction we get a diode with the following characteristics. Electrostatic analysis of a pn diode pnjuntiondiode. A pn junction diode is a two terminal single crystal semiconductor device whose one side is doped with acceptors and other side by donors. Pn junction diode electronics club basic electronics. When one side of an intrinsic semiconductor is doped with acceptor i. Pn junction diode is the most fundamental and the simplest electronics device.
Pn junction diode junction diode symbol and static iv characteristics. Since a junction forms between a p type and n type material it is called as pn junction. Doping with acceptor creates p type semiconductor while doping with donors produces n type. Semiconductor pn junction diode working pn diode vi. Biased pn junction diodes and current flow in this lecture you will learn. The pn junction diode is the typical diode that has been used in the previous circuits. The p positive side contains an excess of holes, while the n negative side contains an excess of electrons in the outer shells of the electrically neutral atoms there. Lecture 4 pn junctions diodes alexandria university. Pn junction diodes form the basis not only of solar cells, but of many other electronic devices such as leds, lasers, photodiodes and bipolar junction transistors bjts. It has a positive p side and a negative n side created by adding impurities to. A pn junction diode is a basic semiconductor device that controls the flow of electric current in a circuit.
The diode conducts when forward bias is applied and it will introduce zero resistance in the circuit. A pn junction diode is made by forming a ptype region of material directly next to a ntype region. This pn diode applications are very useful for beginners. Lecture 15 the pn junction diode i mit opencourseware. Figure 1c gives the circuit symbol of a pn diode, common to all types. Lecture 5lecture 5 pn junction diodes quantitative analysis. Jan 04, 2020 a pn junction is the simplest form of the semiconductor diode. Electrons tunnel from the valence band to the conduction band. Read more pn junction diode and its working principle. In reversebiased pn junction, the electric field is concentrated within a narrow depletion region. The recombination at the junction allows battery current to flow through the pn junction diode.
However, if we have a tendency to were to create electrical connections at the ends of each the ntype and also the ptype materials so connect them to a battery supply, a further energy supply currently exists to beat the potential barrier. They are referred to as photoelectrons and photoholes the applied voltage separates the photocarriers attracting electrons toward. Find materials for this course in the pages linked along the left. The word diode can be explained as di means two and ode is obtained from electrode. 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. In this video lecture i explained about pn junction diode part 1. 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. 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. Chitralekha mahanta, department of electronics and communication engineering,iit guwahati. Figure 1a and b show respectively three and twodimensional views of basic grown junction diode. Working of pn junction diode with biasing, characteristics. A pn junction diode is twoterminal or twoelectrode semiconductor device, which allows the electric current in only one direction while blocks the electric current in opposite or reverse direction. Zero bias no external voltage potential is applied to the pn junction diode. The load resistance r l is connected to these terminals through a p n junction diode d.
Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. A p n junction aggregates the recombination, generation, diffusion and drift effects described in the previous pages into a single device. Click here to visit our frequently asked questions about html5. P n junctions consist of two semiconductor regions of opposite type. In this physics video in hindi we explained the working of a pn junction diode for class 12. As shown in the figure, pn junction diode is a 2 terminal polarity sensitive device.
May 20, 20 may 02, 2020 pn junction diode, pn junction diode characteristics semiconductor electronics class 12 video edurev is made by best teachers of class 12. The transition from avalanche to zener as the primary breakdown mechanism with dopant concentration is shown in figure 5. A diode is a simple device, which can be implemented by a pnjunction, as well as other heterojunction structures. Pn junction diode, pn junction diode characteristics. The pn junction diode is the basic semiconductor diode format. Ee105 fall 2014 microelectronic devices and circuits. 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. A p n junction is the metallurgical boundary between the n and p regions of a semiconductor crystal. The p n junction is the fundamental building block of the electronic age.
These diodes have a very accurate and specific reverse breakdown voltage. Photodetectors pn junction can detect light when reverse biased ptype ntype when the light illuminates the pn junction, the photons energy releases free electrons and holes. This page of application notes section covers pn junction diode applications. 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.
Such junctions show a pronounced rectifying behavior. May 02, 2020 pn junction diode, pn junction diode characteristics semiconductor electronics class 12 video edurev is made by best teachers of class 12. Forward biasing a pn junction diode is very simple. Lecture 7 large and small signal modelling of pn junction.
Review, pn junctions, fermi levels, forward bias prof j. Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 19 prof. This video is highly rated by class 12 students and has been viewed 591 times. There are a few basic concepts to be introduced, such as energy bands, drift and diffusion currents, etc. Gate questions on pn junction diode 1987 to till date. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the p n junction. The diode does not conduct when reverse bias is applied and. A pn junction diode in thermal equilibrium you have already seen a pn junction diode in thermal equilibrium. Abrupt depletion layer approximation let apply bias and calculate current through the pn junction currents in pn junction from sze, 1981. The potential at terminal x with respect to y will vary as a sine function with time.
Silicon a single silicon atom consists of fourteen negatively. Video created by georgia institute of technology for the course introduction to electronics. Smith abrupt junction, full depletion model for the abrupt junction, full depletion model of the pn diode, we can find the potential as a function of position by integrating over the charge. No generationrecombination in the depletion layer 6. A pn junction aggregates the recombination, generation, diffusion and drift effects described in the previous pages into a single device. Are used to allow current to flow in one direction while blocking current flow in the opposite direction. A pn junction diode is a combination of two semiconductor materials, one is ptype semiconductor and another is ntype semiconductor.
Design a circuit that tests the forward voltage v f of a pnjunction diode, so you may measure the voltage yourself, without the use of a special diodetesting meter. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. P n junction diodes form the basis not only of solar cells, but of many other electronic devices such as leds, lasers, photodiodes and bipolar junction transistors bjts. Pn junctions consist of two semiconductor regions of opposite type. Consider the heavily doped p n junction shown to the left and then apply a reverse bias to the junction. The maximum electric field occurs exactly at the pn interface. The pn junction solidstate device theory electronics. Are specifically designed to operate under reverse breakdown conditions. Difference between pn junction diode and zener diode. Lecture 5lecture 5 pn junction diodes quantitative. If the diode is forward biased, it allows the electric current flow.
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. Depletion region created across the pn junction by the initial movement of majority carrier across the junction. Depletion layer opposes only the the majority carrier not minority carrier. Thus a reverse biased pn junction does not conduct current. The conversion of alternating current into direct current is known as rectification. A silicon pn junction diode under reverse bias has depletion region of width of 10 m. Questions you should be able to answer by the end of todays lecture. Pn junctions worksheet discrete semiconductor devices and. Pn junctions and diodes circuits guyeon wei division of engineering and applied sciences.
The diode has two terminals, ptype semiconductor is called. May 06, 2010 p n junction diode a pn junction is known as semiconductor diode. Lecture 6 biased pn junction diodes and current flow. In order to analyse the device in as simple a manner as possible we shall assume that the p n junction is made by. Module 1 lecture 2 pn junction diodes lecture series on basic electronics by dr. Pn junction diode 2 diode introduction a diode is formed by joining an ntype semiconductor with a ptype semiconductor. A p n junction diode is twoterminal or twoelectrode semiconductor device, which allows the electric current in only one direction while blocks the electric current in opposite or reverse direction. The pn junction is the fundamental building block of the electronic age. Lecture 11 pn junction diodes doolittle georgia tech. 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. Also, it explains the phenomenon of shockleyqueisser limit. Pn junction diode baising and its vi characteristics. There are two operating regions and three possible biasing conditions for the standard junction diode and these are. On the other hand, if the diode is reverse biased, it blocks the.
Pn junction tutorial introduction to pn junction diodes. A pn junction is said to be formed only when a bonding force is created between the ptype and ntype semiconductor. 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. Pn junction diode 1 ee105 fall 2014 microelectronic devices and circuits prof. A pn junction is said to be formed only when a bonding force is created between the p type and n type semiconductor. Quantitative p n diode solution depletion regiondepletion regionx x e 0 e 0 e 0 p n application of the minority carrier diffusion equation 0 0 2 2 2 n l p n p p p d g p x p d t p p p l n p p n p n d g n x n d t n 0 2 2 2 since electric fields exist in the depletion region, the minority 0 0 2 p n p p x p d n. Pn junction diode applications pn diode applications. Usually voltage is taken across xaxis and current along yaxis. The p n junction diode we are now in a position to explain the rectifying action of a p n junction diode. It is also called as simply pn junction or semiconductor diode. Most semiconductor devices involve regions with two different kinds of doping, so a pnjunction is present in all of them.
Characteristics of junction diodes given a semiconductor pn junction we get a diode with the following characteristics. This brings many occupied states on the p side into energetic alignment with vacant states on the n side. A k schematic symbol for a pn junction diode p n representative structure for a pn junction diode. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. In the positive half cycle, during the time interval 0 to t2, diode d will be forward biased and conduct, i. Turn on voltage based on the builtin potential of the pn junction reverse bias breakdown voltage due to avalanche breakdown on the order of several volts. The pn junction is a versatile element, which can be used as a. Octavian florescu 2 the pn junction diode schematic diagram p type n type id. When the diode is forwardbiased, it can be used in led lighting applications. 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. Vi characteristics of pn junction diode electronics post. Powerpoint slide on pn junction diode compiled by paridhi gupta.
Large and small signal modelling of pn junction diodes in this lecture you will learn. 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. The p n junction is a versatile element, which can be used as a. Reverse bias brings the conduction band very close to the valence band. Definition, symbol, and types of diodes electrical4u. Lecture 15 the pn junction diode i iv characteristics november 1, 2005 contents. Due to this characteristic, the diode finds number of applications as given below. The pn junction has the very useful property that electrons are only able to flow in one direction.
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