Lecture 1 introduction to semiconductors and semiconductor. The module is based on the driftdiffusion equations, using isothermal or nonisothermal transport models. Semiconductors, diodes, transistors horst wahl, quarknet presentation, june 2001 electrical conductivity. During forward biasing, holes move towards n side and electrons move towards p side. Semiconductor and optoelectronic device physics simulation. Alan doolittle 2 2 ln ln ln i a d bi a i d p n bi n n n q kt v n n n q kt n x n x q kt v movement of electrons and holes when forming the junction for nand1015cm3 in silicon at room temperature.
Electrons and holes remain staying close to the pn junction because negative and positive charges attract each other. Full practical pn junction diode with readings, download pdf. Such junctions show a pronounced rectifying behavior. Schubert quantum mechanics applied to semiconductor devices. Hello friends, today is going to share the sl arora physics pdf for class 12th download sl arora physics vol1 and 2 pdf. Physics stack exchange is a question and answer site for active researchers, academics and students of physics. Sep 10, 2016 pn junction and zener diode 12 class project.
Diodes and diode circuits tlt8016 basic analog circuits 20052006 20 3. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. Dec 31, 2015 pn junction under reverse bias p connected to negative terminal of battery, n connected to positive terminal at n, electrons move towards the positive terminal, creating a larger area of positive charges. 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. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium. Higher physics second in a series of 3 videos on semiconductors. We will refer to this structure as an abrupt pn junction. Device physics i pn junctions junction capacitance martin p. When ptype and ntype materials are placed in contact with each other, the junction behaves very differently than either type of material alone. Similarly, holes flow by diffusion from the ptype side to the ntype side. Apr 05, 2019 pn junction is formed in a single crystal by joining two ntype and ptype semiconductors. If the silicon crys tal is very pure, then the outer four electrons occupy all of the covalent. This textbook introduces the physical concepts required for a comprehensive understanding of pn junction devices, light emitting diodes and solar cells.
Physics is the study of matter and energy and the interaction between them. Because of its electrical properties, silicon is called a semiconductor. When recombination in pn junction occurs, which atom becomes an. The charge in the depletion region per cross sectional area is the depletion width times the concentration of ionic charge qn. Finally, from device physics and i would love to teach. The diffusion of electrons and holes into the depletion layer decreases its width. Band diagram of pn junction under a equilibrium and b forward.
Pn junction is formed in a single crystal by joining two ntype and ptype semiconductors. Since the ntype region has a high electron concentration and the ptype a high hole concentration, electrons diffuse from the ntype side to the ptype side. During the formation of pn junction diffusion process takes place in which the free electrons cross the boundary of the pn and joined with the holes in the ptype to form the negative ion and holes on the n side cause positive ions. This charge transfer of electrons and holes across the pn junction is known as diffusion.
Transmission lines pdf file bipolar junction transistor html file bipolar junction transistor pdf file pn junctions html file pn junctions. Bipolar junction transistor pdf file pn junctions html file. Sl arora physics pdf for class 12th download sl arora. Also i wan to know that is there any relation between barrier potential and energy band gap small band gap small barrier. Electronic engineering ece 1 spring 2017 topic 4 physics of a pn junction sameh a. Module 1 semiconductor pnjunction diodes what are they and what is their purpose. There are a few basic concepts to be introduced, such as energy bands, drift and diffusion currents, etc. The pn junction is a versatile element, which can be used as a. This video covers the formation of the pn junction and how it performs when forward and reverse biased. The concentrations of free carriers injected into the quasineutral regions are small enough so that we can.
Lecture 16 the pn junction diode ii mit opencourseware. How to find barrier potential of pn junction diode physics. Physics of semiconductor devices pn junction depletion width problem a silicon pn diode has a doping of n d 81015 1 cm3 and n a 210 16 1 cm3. Doped semiconductors ntype materials ptype materials diodes and transistors. The pn junction forms the basis of the semiconductor diode. Electron current density is a combination of drift and diffusion currents, which must.
Semiconductor, silicon, pn junction, forward bias, reverse bias, diode. Aug 10, 2015 diode theory pn junction, biasing, characteristic curves a diode is a specialized electronic component with two electrodes called the anode and the cathode. The pn junction solidstate device theory electronics. Electric field distribution in a reversebiased pn junction 1 problem. Silicon a single silicon atom consists of fourteen negatively. P type and n type semiconductors, takenseparately are of very limited use. Pn junction under reverse bias p connected to negative terminal of battery, n connected to positive terminal at n, electrons move towards the positive terminal, creating a larger area of positive charges. The recombination at the junction allows battery current to flow through the pn junction diode. To learn more on the formation, forward and reverse bias, with formula, visit byjus. Frequently we will deal with pn junctions in which one side is. In addition,lets make the following simplifying assumptions. Negative charge stops electrons from further diffusion positive charge stops holes from further diffusion the diffusion forms a dipole charge layer at the pn junction interface.
Specifically, current will flow readily in one direction forward biased but not in the other reverse biased, creating the basic diode. If you have pregion on the left and nregion on the right then electrons would have to climb a potential barrier going from n to p move uphill. Pn junction free download as powerpoint presentation. The width of these p and n layers depends on how heavily each side is. 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. Semiconductor diodes the diode is the simplest type of semiconductor device. Physics of pn junctions and semiconductor devices springerlink.
Hitech gadgets, modern machinery, gigantic skyscrapers, speedy trains, superior infrastructure are some of the marvels of physics. Diodes are electronic check valves which allow current to flow freely in one direction, but block current flow in the opposite direction. Specific designs are the result of the understanding of the physics of pn junction hv breakdown, gain variation at high currents, current. An ideal junction in which there are no generationrecombination processes in depletion region. Module 2 essentially, they serve the same function in circuits, as the valves in your heart and. Sl arora physics pdf is very important for the students who are in class 11th or class 12 class. Semiconductor physics semiconductors and diodessemiconductors. Being free particles, electrons start diffusing from ntype material into pmaterial being free particles, holes, too, start diffusing from ptype material into nmaterial have they been neutral particles, eventually all the free electrons. How to find barrier potential of pn junction diode. For your knowledge, i am telling you that sl arora physics vol1 is for 11th class students and sl arora physics vol2 book is for 12th class students. 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. Most semiconductor devices involve regions with two different kinds of doping, so a pn junction is present in all of them. Sl arora book is important for maths and bio students because all the concept of sl arora.
Olav torheim, elementary physics of pn junctions, 2007. The difference between an insulator and a semiconductor lies in the size of the band gap. What happens when we apply voltage to the pn junction. When a pn junction is used as a detector of charged particles or of photons. Pn junction diode and its characteristics in chapter 1 understanding the pn junction, we have seen how a pn junction is formed from a ptype and ntype semiconductor. Apr 02, 2018 higher physics second in a series of 3 videos on semiconductors. Diodes and diode circuits tlt8016 basic analog circuits 20052006 a.
They are also called pn diodes in analogy with vacuum diodes. The pn junction is fundamental to the operation of devices such as the solar cell, the diode, and certain types of transistors. Diode theory pn junction, biasing, characteristic curves a diode is a specialized electronic component with two electrodes called the anode and the cathode. We have also learned about diffusion current, depletion region. Pn junction one of the crucial keys to solid state electronics is the nature of the pn junction. I s ntroduction to 1 emiconductors pearson education.
At p, holes move towards the negative terminal, creating a large area of negative charges. Introduction to semiconductors and semiconductor devices a background equalization lecture reading. It reveals the magic behind the wonderful existence of natural phenomenon. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal. It is a passive element because the current flows in one direction. It acts as a diode, which can serve in electronics as a rectifier, logic gate, voltage regulator zener diode. Diodes and diode circuits tlt8016 basic analog circuits 20052006. In terms of water models, it can be thought of as a oneway water valve, or check valve, that only lets water. Pn junctions consist of two semiconductor regions of opposite type. The pn junction is the fundamental building block of the electronic age. The total charge on each side of a pn junction must be equal and opposite to maintain a neutral charge condition around the junction. Adapted from semiconductor device physics and design umesh mishra and.
Pn junction physics from ece 340 at california state university, northridge. Thus, currents of ntype and ptype majority carriers flow toward the junction. 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. Basic diode electronics introduction to diodes the pn junction the pn junction is a homojunction between a ptype and an ntype semiconductor. Nov, 20 i want to know that when a pn junction diode is formed and barrier potential is setup then how can we determine the same theoretically. Difference between pn junction diode and zener diode. We will assume, unless stated otherwise, that the doped regions are uniformly doped and that the transition between the two regions is abrupt. Pn junction lab free to use on allows simulation and study of a pn junction diode with different doping and materials. What are the depletion width in the nregion, the depletion width in the pregion, and the builtin potential at 300k.
If the depletion layer region has a distance d, it therefore must therefore penetrate into the silicon by a distance of dp for the positive side, and a distance of dn for the negative side giving a relationship between the two of. The zener diode, on the contrary, allows flowing of the reverse current. 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. Writing a book on semiconductor device physics and design is never complete and probably never completely satisfying. Forward bias current flows reverse bias no current flow. Pn junctions are formed by joining ntype and ptype semiconductor materials, as shown below. Pdf experiment on the physics of pn junction giacomo.
Welcome to physics wiki we are currently editing over 162 articles, and you can help. The semiconductor module provides dedicated tools for the analysis of semiconductor device operation at the fundamental physics level. Pn junction physics ece340 electronics i pn junction. Semiconductor physics the pn junction biasing the pn junction the diode trouble shooting. Semiconductor devices have made a major impact on the way we work and live. Physics of semiconductor devices pn junction depletion width.
I want to know that when a pn junction diode is formed and barrier potential is setup then how can we determine the same theoretically. 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. Physics of semiconductor devices pn junction depletion. Diode is the simplest semiconductor element, which has one pnconnection and two terminals.