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. Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 20 prof. Spring 2003 ee lecture 10, slide 4 idealized junctions. Now that you are familiar with p and ntype materials, how these materials are joined together to form a diode, and the function of the diode, let us continue our discussion with the operation of the pn junction.
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. This time consists of a transient and an interval of time before the diode attains a steady state. With proper biasing, pn diode allows current to flow in single direction. The diode is firmed by doping a semiconductor like silicon or germanium with trivalent impurity e. 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. Zero bias no external voltage potential is applied to the pn junction diode. The pn junction has the very useful property that electrons are only able to flow in one direction. 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.
Junction diodes questions and answers electronics post. Semiconductor pnjunction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. Majority carriers in quasiequilibrium with barrier 4. 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. Simplified physical structure construction on a cmos chip. Vi characteristics of pn junction diode in 3biasing modes. This allows electrical current to pass through the junction only in. They are also called pn diodes in analogy with vacuum diodes. It is used in the construction of transistors, fet, gates and many other types of integrated circuits. Forward biasing a pn junction diode is very simple. Review, pn junctions, fermi levels, forward bias prof j. Negligible scl generation and recombination relate minority populations at qnr edges, x p and x n, to v ab use nx p, px n to find hole and electron.
The pn junction is a versatile element, which can be used as a. If the diode is forward biased, it allows the electric current flow. The valence band and conduction band in ntype material are slightly lower than that of ptype material. The pn junction diode is the basic semiconductor diode format. The doping profile is our starting point to analyze pn junction electrostatics, since it combines the information given for n d and n a. A pn junction is formed by diffusing a ptype material to an ntype wafer and there are several other ways as well, see your text. These materials are ntype, having electrons are majority carrier and ptype material, having holes are majority carrier. Lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents. 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.
P type and n type semiconductors, takenseparately are of very limited use. 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. 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. From the above, it follows that zero power dissipation occurs in an ideal diode. 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.
Physics project for class 12 on effect of pn junction on. If positive potential is applied to the top terminal as shown in fig. These are the easiest and basic diodes available in and use pn junction characteristics like depletion layer, diffusion and drift current. At the point of the junction, which we call the metallurgical junction, is where n d n a 0. Vincent chang currentvoltage characteristic v v t 1 i i s e. Abrupt depletion layer approximation let apply bias and calculate current through the pn. Octavian florescu 2 the pn junction diode schematic diagram ptype ntype id. A pn junction is said to be formed only when a bonding force is created between the ptype and n. The pn junction is the fundamental building block of the electronic age.
By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. As a leading global manufacturer of crushing, grinding and mining equipments, we offer advanced, reasonable solutions for any sizereduction requirements including, physics project for class 12 on effect of pn junction on half way rectifier, quarry, aggregate, and different kinds of minerals. A pn junction diode is made by forming a ptype region of material directly next to a ntype region. A pn junction with open terminals excluding minority carriers f.
Pn junction diode applications pn diode applications. Najmabadi, ece65, winter 2012 high concentration of h on the p side holes diffuse towards the junction high concentration of. A pn junction diode is a twoterminal electronics element, which can be classified as either step graded or linear graded. 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. It is the most essential and the basic building block of the electronic device.
Since a junction forms between a p type and n type material it is called as pn junction. No generationrecombination in the depletion layer 6. Pn junction diode is a device made of two semiconductor material joined together with the required amount of impurity. This pn diode applications are very useful for beginners. Pn junction diode is one of the fundamental elements in electronics. Such junctions show a pronounced rectifying behavior.
A pn junction is a boundary or interface between two types of semiconductor materials, ptype and ntype, inside a single crystal of semiconductor. Pn junction tutorial introduction to pn junction diodes. As shown in the figure, pn junction diode is a 2 terminal polarity sensitive device. The word diode can be explained as di means two and ode is obtained from electrode. 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. Working of pn junction diode with biasing, characteristics. Pn junction diode and characteristics of pn junction diode. 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. Semiconductor pn junction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i.
Smith department of eecs university of california, berkeley eecs 105 spring 2004, lecture 19 prof. Physics project for class 12 on effect of pn junction on half way rectifier products. Pn junction diodes as the name suggests are diodes made up by combining one p type and one n type semiconductor. 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. The contact surface between the layers of ptype and ntype semiconductor pieces plated together so as to form a pn junction is called the pn junction. Pn diodes forward bias, small signal model, bjts prof j. Pnjunction diode and diode circuits 1 main properties of semiconductors 2 the pnjunction in equilibrium 3 the i v characteristics of the pnjunction 4 deviations from the ideal diode 5 analysis of the diode circuits 6 rectifier circuits. Introduction to pn junction the engineering projects. 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. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. The pnjunction is the root for semiconductor diodes. Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. Silicon a single silicon atom consists of fourteen negatively. The energy gap between the valence level and the conduction level is midway between that of insulators and conductors such as metals, and thermal energy causes.
Smith context this lecture will discuss zdiode currents in forward and reverse bias 6. Pnjunction diode characteristics ppt documentation. 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. Specialpurpose diodes 129 actually contain two pn junctions that are connected in reverseparallel i. Why is silicon preferred over germanium in the manufacture of semiconductor devices. 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. We prefer to read our article on pn junction first before reading this guide for maximum understanding. Draw the energy level diagram of a pn junction and explain how a junction barrier is developed across an unbiased junction. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. A semiconductor pn junction diode is a two terminal electronic device that allows current in only one direction. The pn junction is a junction formed together by ptype semiconductor and ntype semiconductor material. But before we can understand how the pn junction works, we must first consider current flow in the materials that make up the junction and what happens. 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. This page of application notes section covers pn junction diode applications.