Image source forward biasing a pn junction diode is very simple. The pn junction is also the basic building block of a variety of other devices, and the basic techniques used for the analysis of the pn junction can be. In the case of normal diodes the diode damages at the break down voltage. This diode can exhibit two states of high and low resistance clearly which can be used alternatively. The pn junction diode is the most basic form of semiconductor device and its technology forms the basis of many other devices. 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. Pn junction, types, construction and working circuit digest. 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. In general, semiconductors in which metals are bonded to n. In the most basic junction, the pn junction, a diode is formed. Diode seminar ppt and pdf report download study mafia.
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. The diode conducts when forward bias is applied and it will introduce zero resistance in the circuit. The junction region or the transition region where the nature of the semiconductor material changes from ptype to ntype is usually very thin, typically 106 to 104 cm wide depending on the method of concentration. The pn junction diode characteristics and operation is closely connected to the behaviour of the carriers in the junction formed at the boundary between the ptype and ntype materials. The excerpts presented, from the authors book crystal fire, track the work of an unsung hero of semiconductor history. These diodes are the normal pn junction diodes, which allow current to flow through them in only one direction and stop in the other direction. Department of electrical engineering college of engineering. Conducts excellently even in reverse biased condition. The diode is simple in its basic concept, being formed from the junction of ntype and ptype materials, although in reality the manufacture and theory of operation are more. Nov 03, 2005 lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents. Pn junction can basically work in two modes, a battery is connected to the diode oforward bias mode positive terminal connected to pregion and negative terminal connected to n region areverse bias mode negative terminal connected to pregion and positive terminal connected to n region. Well cover the diode definition further, and lay the foundation of why a diode acts like it does when an ndoped material and a pdoped material are put together.
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. A simple zener diode voltage regulator in the voltage regulator the zener diode operates in the breakdown region, which ensures approximately constant voltage across it. Introduction to pn junction the engineering projects. Pn junction diode baising and its vi characteristics. Thereafter, based on the exclusion zone, and the diode is not. Working principle of pn junction semiconductor diode. Initially vary regulated power supply rps voltage v s in steps of 0.
The cathode is marked with the silver colour or colour band. Pn junction diode and characteristics of pn junction diode. Such junctions show a pronounced rectifying behavior. Pn junction diode is a two terminal device, the characteristics of diode depends on the polarity of the external potential applied to the pn junction diode. The pn junction is the fundamental building block of the electronic age. 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 junctions consist of two semiconductor regions of opposite type. If both pside and nside of the diode are lightly doped, depletion region at the junction widens. This allows electrical current to pass through the junction. It will help you to grasp concepts behind pn junction even better. Today semiconductor pn junction diode devices are experiencing substantial growth.
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. Zener diodes vary in specifications such as nominal working voltage, power dissipation, maximum reverse current, and packaging. Forward bias and reverse bias pn junction diode jee. For designing the diodes, silicon is more preferred over germanium. Doping with acceptor creates p type semiconductor while doping with donors produces n type. Equivalent circuit of diode, dynamic resistance, zener diode. A pn junction or pn diode consists of a semiconductor having two regions, a pregion and nregion with a junction in between. A diode is also a tool that exclusively permits unidirectional flow of current if the diode is operated at a particular voltage level. Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. It is acting as normal diode while forward biasing. The junction plays an important role in the development of the diode which is the building block of most of the semiconductor devices like transistors, bjts, solar cells and integrated circuits.
The pn junction is the basic root for semiconductor diodes. Pn junction tutorial introduction to pn junction diodes. A schottky barrier diode sbd is a device in which a semiconductor and a metal such as molybdenum are bonded instead of a pn junction. Diodes and diode circuits tlt8016 basic analog circuits 20052006 11 3. Once the current starts increasing vary v s in steps of 0. Semiconductor pn junction diode working pn diode vi. One terminal of pn junction diode is anode and other is cathode. This pn diode applications are very useful for beginners. The diode or pn junction was the first form of semiconductor device to be investigated in the early 1940s when the first real research was undertaken into semiconductor technology. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. This process is a building block for the development of the diode. This is a normal single pn junction diode which is especially designed for switching purposes. This course presents indepth discussion and analysis of pn junction and metalsemiconductor contacts including equilibrium behavior, current and capacitance responses under bias, breakdown, nonrectifying behavior, and surface effect. Doped semiconductors ntype materials ptype materials diodes and transistors.
Apr 23, 2018 semiconductor pn junction diode is the simplest semiconductor device. Pn junction diode applications pn diode applications. 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. Coed school kolar road bhoapl department of physics project report investigatoryproject on pn junction and diodes project report submitted by govind patel submitted to mrs ratna. Module 2 essentially, they serve the same function in circuits, as the valves in your heart and veins do in your body. A pn junction is a boundary or interface between two types of semiconductor materials, ptype and ntype, inside a single crystal of semiconductor. 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. Semiconductor devices have made a major impact on the way we work and live. P type and n type semiconductors, takenseparately are of very limited use. A zener diode when reverse biased can either undergo avalanche break down or zener break down. Of 10 to 20 is the diode should be locked and the output voltage v 0. Heterojunction pn junction at equilibrium coursera. The pn junction is a versatile element, which can be used as a. They are also called pn diodes in analogy with vacuum diodes.
The diode is formed by joining both ntype and ptype semiconductors together. There are three types of junction diodes, as shown in the following figure. In a pn junction diode, two types of semiconductorptype and ntype are fused together where one part consist of ntype semiconductors and the other one. The junction diodes are the normal pn junction diodes but differ in construction. The ptype material is formed by the addition of impurity with trivalent doping. This is the basic construction of the pn junction diode. Zener diode is a pn junction diode specially designed to operate in the reverse biased mode. To find cutin voltage for silicon pn junction diode. Semiconductor devices such as diodes, transistors and ics contain pn junctions, and will not function correctly if they are illuminated by unwanted electromagnetic radiation light of wavelength suitable to produce a photocurrent. Iv characteristics, working and uses of optoelectronic junction device, solar cell, photodiode, led. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner work ings of the pn junction.
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 ntype aspect, the diode is speculated to be in forward biased condition. Many materials, such as most metals, allow electrical current to flow through them these are known as conductors materials that do not allow electrical current to flow through them are called insulators pure silicon, the base material of most transistors, is. Here you may find a good video with animation, which explains the formation of pn junction. Since a junction forms between a p type and n type material it is called as pn junction. Sep 05, 2019 semiconductor pn junction diode working principle. Diodes and transistors university of california, berkeley. Semiconductor pn junction diode is the simplest semiconductor device. Construction the zener diodes operation depends on the heavy doping of its pn junction. A zener diode when forward biased behaves like an ordinary pn junction diode. The current in the pn junction diode can only flow from one side to the other.
Topics covered bee pdf notes of module 1 are listed below. An ideal pn junction diode is based on the following basic assumption. This is the simplest semiconductor device but this is very important and most useful in electronic circuits. In general a diode iv curve can be approximated by. The pn junction has been the most common rectifier used in the electronics industry. For integrated pn diodes, no special process steps available. Feb 11, 2019 when semiconductors of different types are put next to each other, interesting things happen.
The light emitting diode is specially doped and made of a special type of semiconductor. Pdf the photoelectronic characteristic of a pn junction device developed by thermal deposition of cu 3. The pn junction is the basic structure of solar cell, lightemitting diode, and diode laser, and is present in all types of transistors. Nonideal pn junction diodes engineering libretexts. Coed school kolar road bhoapl department of physics project report investigatoryproject on pn junction and diodes project report submitted by govind patel submitted to mrs ratna hajela registerationno. Diode schematic symbol and actual picture of a common 1n914 diode the black stripe in the picture is the cathode. A junction is formed between the ptype and ntype layers. A pn junction has rectifying currentvoltage iv or iv characteristics as shown in fig. Open closed 2 semiconductor pn junction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. The direction of external voltage applied in reverse bias is opposite to that of external voltage applied in forward bias. The junction plays an important role in the development of the diode which is the building block of most of. Sandia report sand20103284 unlimited release printed april, 2011 analytic 1d pn junction diode photocurrent solutions following ionizing radiation and including timedependent changes in the carrier lifetime bert kerr, carl l. With the help of the curve we can understand that there are three regions in which the diode works, and they are. It has a particular voltage known as break down voltage, at which the diode break downs while reverse biased.
In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. But for alex molinaroli, they were the start of a career that took him from the cec all the way to the top of one of the most prominent energy solutions companies in the world. It was found that small point contact diodes were able to rectify some of. Semiconductor fundamentals doping pn junction the diode equation zener diode led what is a semiconductor. I have developed a second chapter on the series, which explains the characteristics of pn junction diode. 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. Basic semiconductor device physics, which is useful to understand how diodes work covered in more detail in ecen 370 razavi ch3 diode models and circuits. Working of pn junction diode with biasing, characteristics. Depletion region created across the pn junction by the initial movement of majority carrier across the junction. Forward biasing a pn junction diode is very simple. This page of application notes section covers pn junction diode applications. This course can also be taken for academic credit as ecea 5631, part of cu boulders master of science in electrical engineering degree. Without knowing the basic idea of ptype and ntype materials, pn junction, depletion region and barrier potential, we are unable to understand the working of a diode as well as a transistor and many other electronic devices.
The small control boxes lining swearingens halls may be unassuming. 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. This is to certify that project work titled a study on pn junction and diodes being submitted by drishti dua a student of class xiid. Certificate this is to certify that project work titled a study on pn junctions and diodes being submitted by govind patel a student. Apr 05, 2019 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. A pn junction diode allows electric charges to flow in one direction, but not in the opposite direction. Diode is the two terminal polarised electronic semiconductor device. This diode can emit light when it is in the forward biased state. Any pn junction, if illuminated, is potentially a photodiode. Depletion layer opposes only the the majority carrier not minority carrier. As shown in the figure, pn junction diode is a 2 terminal polarity sensitive device. Pn junction diode is a diode which can be used as a rectifier, logic gate, voltage stabiliser, switching device, voltage dependent capacitor and in. The vast majority of all diodes are the pn diodes found in cmos integrated circuits, which include 2 diodes per pin and many other internal diodes.
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. The depletion region formed in the diode is very thin and the electric field is consequently very high even for a small reverse bias voltage of about 5 v, allowing electrons to tunnel from the valence band of the p type material to the conduction band of. Within this the charge carriers from the pn junction area flow from. Semiconductors, diodes, transistors horst wahl, quarknet presentation, june 2001 electrical conductivity. A pn junction is a boundary or interface between two types of semiconductor materials, ptype. The word diode can be explained as di means two and ode is obtained from electrode. There are more phenomena at work here than just diffusion. From the above, it follows that zero power dissipation occurs in an ideal diode. The junction capacitance of this diode is made very low so as to minimize other effects. Hence comparing the schematic symbol to the pn junction in figure 4, we see the anode is the ptype semiconductor and the cathode is the ntype semiconductor.
Contd notes and anderson2 sections part 2 preface and sections 5. Schottky diode is a metalsemiconductor junction diode that has less forward voltage drop than the pn junction diode and can be used in highspeed switching applications. Keiter prepared by sandia national laboratories albuquerque, new mexico 87185 and livermore, california 94550 sandia national laboratories is a. Silicon a single silicon atom consists of fourteen negatively. Sep 10, 2016 pn junction and zener diode 12 class project. A pn junction is the metallurgical boundary between the n and pregions of a. Oct 21, 2020 a pn junction diode is a kind of semiconductor diode that made up of a joining ptype and ntype semiconducting layers. Announcements 2 lab 4 due mar 4 r lab 5 due mar 9 t hw4 due mar 10. The pn junction is a junction formed together by ptype semiconductor and ntype semiconductor material.
Oct 28, 2020 a light emitting diode led is a special type of pn junction diode. The pn junction diodes made from silicon semiconductors works at higher temperature. This device is a combination of ptype and ntype semiconductor material hence it is also known as pn junction diode. Switching diodes switching diodes, sometimes also called small signal diodes, are single diodes in.
415 1092 294 828 572 961 955 1431 1597 961 1140 1388 528 31 417 126 407 1007 253 503 56 1628 151