Vincent chang currentvoltage characteristic v v t 1 i i s e. When the diode is in forward conduction, the voltage drop across the diode is constant. Formation of a pnjunction overview joining ntype material with ptype material causes excess electrons in the ntype material to diffuse to the ptype side and excess holes from the ptype material to diffuse to the ntype side. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal.
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. 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. No generationrecombination in the depletion layer 6. The word diode can be explained as di means two and ode is obtained from electrode. If the diode is forward biased, it allows the electric current flow. Pnjunction diode characteristics ppt documentation. A pn junction is the simplest form of the semiconductor diode. Pn junction theory for semiconductor diodes electronicstutorials. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. Once the applied bias voltage is increased to a value where the reverse voltage across the diode reaches the breakdown value of the diode which is vbr, the reverse current begins to increase rapidly.
The term junction refers to the boundary interface where the two regions of the semiconductor meet. Explain the formation of potential barrier and depletion layer. 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. The name diode is derived from diode which means a device that has two electrodes. The pn junction diode is the basic semiconductor diode format. Image source forward biasing a pn junction diode is very simple. Diodes are made from semiconductor materials, mainly silicon. 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. This presentation is a very informative piece on pn junction diode an important part of electronics education. 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. One of the most common applications of the diode is the pn junction. Device design assessment of gan merged pin schottky diodes. Lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents.
When a reverse bias is applied across a pn junction diode, there is an extremely small reverse current ir through the pn junction due to minority carriers. 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. Pn junction diode and diode characteristics electronicstutorials. However, if we join or fuse these two semiconductor materials together they behave in a very different way merging together and producing what is generally. Cbse ncert notes class 12 physics semiconductor electronics. Pdf the photoelectronic characteristic of a pn junction device developed by thermal deposition of cu 3 n bse 4. A pn junction is a junction formed by joining ptype and ntype semiconductors together in very close contact.
The region on the left is ptype with an acceptor density na, while the region on the right is ntype with a donor density nd. Pn junction tutorial introduction to pn junction diodes. Silicon a single silicon atom consists of fourteen negatively. Convert a part of the ptype semiconductor into ntype silicon semiconductor by adding a small quantity of pentavalent impurity. Why is silicon preferred over germanium in the manufacture of semiconductor devices. Junction diodes questions and answers electronics post. Near the junction, electrons diffuse across to combine with holes, creating a depletion region. The energy level sketch above right is a way to visualize the. A pn junction is a boundary or interface between two types of semiconductor materials, ptype. Najmabadi, ece65, winter 2012 high concentration of h on the p side holes diffuse towards the junction high concentration of.
Such junctions show a pronounced rectifying behavior. 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. This pn diode applications are very useful for beginners. Pdf semiconductor pn junctions are elementary building blocks of many electronic devices such as transistors, solar cells, photodetectors, and. Vi characteristics of pn junction diode in 3biasing modes. 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. This pn junction can be used to operate and implement the functions of a diode because it can conduct considerable current in the forward direction and roughly no current in the reverse direction. 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. A pn junction diode is made by forming a ptype region of material directly next to a ntype region. If an external potential is applied to the terminals of pn junction, it will alter the potential between the p and nregions. Pn junction diode in the reversebiased configuration is sensitive to light from a range between 400nm to nm, which includes visible light. Pn junctions consist of two semiconductor regions of opposite type.
A pn junction is the basic building block of many semiconductor devices like diodes, transistor etc. This page of application notes section covers pn junction diode applications. 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. The pn junction has the very useful property that electrons are only able to flow in one direction. Simplified physical structure construction on a cmos chip.
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. This is because the negative voltage pushes or repels electrons towards the junction giving them the energy to cross over and combine with the holes being. The dopants are assumed to be shallow, so that the electron hole density in the ntype ptype region is. Similarly, holes flow by diffusion from the ptype side to the ntype side. Forming a pn junction doping one side of a piece of silicon with boron a ptype dopant and the other side with phosphorus an ntype dopant forms a pn junction. The pnjunction is the root for semiconductor diodes.
The forward voltage drop is an intrinsic property of the semiconductor material used to make the pn junction and is related to the band gap. School of information science and technology, shanghaitech university. The pn junction is the fundamental building block of the electronic age. Pn junction diode, characteristics and applications 2020.
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. As shown in the figure, pn junction diode is a 2 terminal polarity sensitive device. 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. These electrons are not bound and are free to move about. The junction diode basic operation the diode is fabricated of a semiconductor material, usually silicon, which is doped with two impurities. Pn junction diode pn diode is a semiconducting device,that allow current to flow in one direction. Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. Iiin semiconductors wide energy bandgap, large critical electrical field, and good thermal dissipation. 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. Since a junction forms between a p type and n type material it is called as pn junction. Pn junction diode applications pn diode applications.
The diode is firmed by doping a semiconductor like silicon or germanium with trivalent impurity e. Pn junction diode baising and its vi characteristics. P type and n type semiconductors, takenseparately are of very limited use. Abrupt depletion layer approximation let apply bias and calculate current through the pn. When the diode is forwardbiased, it can be used in led lighting applications. In general a diode iv curve can be approximated by. 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. Lecture 15 the pn junction diode i iv characteristics november 1, 2005 contents. Working of pn junction diode with biasing, characteristics.
A pn junction with open terminals excluding minority carriers f. One side is doped with a donor or ntype impurity which releases electrons into the semiconductor lattice. Characteristics of junction diodes technical articles. Definition, symbol, and types of diodes electrical4u.