The most common type of semiconductor diode is the silicon diode. Diodes and transistors pdf 28p this note covers the following topics. It is one of the simplest semiconductor devices as. Semiconductor pn junction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. From the above, it follows that zero power dissipation occurs in an ideal diode. Lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents.
Jan 29, 2019 pn junction diode is one of the fundamental elements in electronics. A pn junction is a boundary or interface between two types of semiconductor materials, ptype and ntype, inside a single crystal of semiconductor. The other differences between the pn junction and zener diode are explained below in the comparison chart. This is the basic construction of the pn junction diode. Semiconductor diode under biasing definition, examples, diagrams. Diodes incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel. Pn junction diode applications physics and radioelectronics. Lecture 16 the pn junction diode ii free online course. Such junctions show a pronounced rectifying behavior. The pn junction is of great importance as it is the main control element for the semiconductor devices.
The device was named after clarence zener, who discovered this electrical property. At the point of the junction, which we call the metallurgical junction, is where n d n a 0. The diode uses the properties caused by the depletion area of the junction. Pn junctions consist of two semiconductor regions of opposite type. 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. They are also called pn diodes in analogy with vacuum diodes. The shaded regions below illustrate the increase in the characteristics of the space charge region due to an externally applied reverse bias, v d. Are specifically designed to operate under reverse breakdown conditions. Region to the left of yaxis vcb negative here both junctions are.
Silicon, ptype silicon, diode, water analogy of diodes, diode applications, transistor, transistor types, bjt types, npn bjt, bjt water analogy, npn transistor in a complete circuit, jfet, optoelectronics, led 101, visiblelight led, tricolor led, photoresistors, photodiode. 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. Pn junction tutorial introduction to pn junction diodes. Aug 28, 2014 16 the pn junction a pnjunction is formed at the boundary between the two regions ntype and p type semiconductors a diode is created. In a similar way the positive holes in the ptype are attracted to the free electrons in the ntype. The electric field opposes the diffusion of holes in the n region and free electrons in the p region. When ie 0, lc icbo icbo is collector to base current with emitter epen below this line we have cutoff region here both junctions are reverse biased saturation region. Lecture 15 the pn junction diode i free online course. Depletion region approximation states that approximately no free carriers exist in the space. Ee105 fall 2014 microelectronic devices and circuits. When the diode is forwardbiased, it can be used in led lighting applications.
The pn junction is the fundamental building block of the electronic age. Temperature coefficient of silicon junction transition capacity the transition capacity of a pn junction is a useful nonlinear capacitor because it. It is the electrical characteristics of the junction rather than the semiconductor sample material that determines the electrical behavior of the entire structure. There are two distinct bias conditions for a pn junction diode. A pn junction is a boundary or interface between two types of semiconductor materials, ptype. Biased pn junction when a positive voltage is appliedon p side, the equilibrium is destroyed and a net current can flow 9 simplifyingassumptions. Download basic electronics download free online book chm pdf. If a voltage drop is applied from n to the pside of the. Thus, we call region 2 of the pn junction diode curve. A bipolar junction diode is basically a pn junction with conducting terminals attached to each side of the junction. Write down all circuit equations and simplify as much as possible 2.
Formation of pn junction in actual practice, a pn junction will not be formed if a ptype. As the depletion area has very few free chargecarries it acts effectively as an insulator. Essentially, this region of the junction diode curve describes an approximate i. 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. Use the diode equation for that state to solve the circuit equations and find i d and v d 3.
This is in contrast to the metalsemiconductor schottky diode discussed in chapter 10, which is known as a majority carrier device. Image source forward biasing a pn junction diode is very simple. 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. Eb junction forward biased cb junction reverse biased lc is positive, vcb is positive lc increases with ie cut off region.
The major difference between pn junction and the zener diode is that the pn junction diode allows current to pass only in the forward direction, whereas the zener diode allows the current to flow both in the forward and the reversed direction. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. By applying a negative voltage reverse bias results in the free charges being pulled away from the junction resulting in the depletion layer width being increased. The pn junction is a versatile element, which can be used as a.
Volume ii 2nd edition modular series on solid state dev. Pn junction diode and characteristics of pn junction diode. 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. Note of pn junction diode by prabhat goud material pdf. 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. 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. The pn junction diode is the typical diode that has been used in the previous circuits. A zener diode is a type of diode that permits current not only in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as zener knee voltage or zener voltage. Diode pn junction when p and n type silicon are brought together during manufacture, a junction is created where the p type and n type materials meet, and holes close to the junction in the p type silicon are attracted into negatively charged n type material at the other side of the junction.
Silicon a single silicon atom consists of fourteen negatively. The junction diode basic operation the diode is fabricated of a semiconductor material, usually silicon, which is doped with two impurities. A pn junction diode is a twoterminal electronics element, which can be classified as either. Pn junction diode 9 reverse bias external reverse bias adds to the builtin potential of the pn junction.
Semiconductor pn junction diodes can be formed from materials other than silicon, such as germanium, selenium, and a host of semiconductor materials used in. Pn junction diode 10 depletion width increases with reverse bias voltage. Lecture 11 pn junction diodes doolittle georgia tech. A pnjunction diode is formed by joining together ntype and ptype silicon. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. The electrical characteristics of leds are the same as normal. These electrons are not bound and are free to move about. Download pdf of note of pn junction diode by prabhat goud material offline reading, offline notes, free download in app, engineering class handwritten notes, exam notes, previous year questions, pdf free download. P type and n type semiconductors, takenseparately are of very limited use. A pn junction diode is referred to as a minority carrier device since its current conduction is controlled by the minority carrier diffusion process i. 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 k schematic symbol for a pn junction diode p n representative structure for a pn junction diode zener diodes. Jan 21, 2019 what is a pn junction when a ptype semiconductor is suitably joined to an ntype semiconductor, the contact surface is called pn junction. This presentation is a very informative piece on pn junction diode an important part of electronics education.
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