Octavian florescu 2 the pn junction diode schematic diagram ptype ntype id. Fabrication of pnjunction diode by ic fabrication process. Since the pn junction demonstrates such a unipolar rectifying response to the applied voltage it is called a pn diode and is denoted in circuit diagrams as a following symbol. Objective the objective of this experiment is to measure the iv curve for pn junction diode and to understand the. This action of pn junction diode enables us to use it as a rectifier. 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. Such junctions show a pronounced rectifying behavior. 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. Semiconductor pn junction diodes physically, diodes are formed by the interface between two regions of oppositely doped semiconductor i. Pn junction diode and diode characteristics electronics tutorials. There are three types of junction diodes, as shown in the following figure. Apparatus the following apparatus were used in the experiment. In so doing, we derive the socalled ideal diode equation. Pn junction diode 1 structure of a pn junction a pn junction diode consists of a piece of ptype semiconductor bonded to a piece of ntype leads are attached to both ends, usually by soldering lead attached to ptype end is the anode lead attached to ntype end is the cathode in order for correct operation, both ntype.
The pn junction has been the most common rectifier used in the electronics industry. Diodes and diode circuits tlt8016 basic analog circuits 20052006. Silicon a single silicon atom consists of fourteen negatively. The pn junction diodes chapter 1 content semiconductor the pn junction diode diode characteristic diode approximation diode. A zener diode when forward biased behaves like an ordinary pn junction diode. All real diodes exhibit this behavior, but only zener diodes are normally.
Diodes and diode circuits tlt8016 basic analog circuits 20052006 a. The direction of external voltage applied in reverse bias is opposite to that of external voltage applied in forward bias. When a ptype and ntype material are brought in contact, a number of interesting properties arise. When a voltage is applied across the junction, a 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. P n junction theory and diodes part i gate problems. The pand ntype regions are referred to as anode and cathode respectively.
Ece 255, pn junction and diode 16 january 2018 in this lecture we would continue with the discussion of the pnjunction which is important for the understanding of the working of a diode. The word diode can be explained as di means two and ode is obtained from electrode. Despite its simplicity, and marginal utility in practice, the formalism provides deep insight into the physical operation of the diode as a starting point for more detailed analysis. The same number of minority carriers are being swept. Zener diode is a pn junction diode specially designed to operate in the reverse biased mode. Pn junction diode the symbol of diode is shown in fig.
The pn junction is the fundamental building block of the electronic age. P n reverse bias potential attracts the majority carriers away from the pn junction widening the depletion region. From the above, it follows that zero power dissipation occurs in an ideal diode. The junction diodes are the normal pn junction diodes but differ in construction.
They are also called pn diodes in analogy with vacuum diodes. 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. Contd notes and anderson2 sections part 2 preface and sections 5. Contains a ptype and an ntype region in a closed boundary. Questions you should be able to answer by the end of todays lecture. A pn junction at equilibrium is characterized by a depletion region where there are. Pdf semiconductor pn junction diodes jeeva bhoopathy. Direction of hole flow direction of conventional current c.
Reverse saturation current in a silicon pn junction diode nearly doubles for very a. It is the most fundamental device element that forms the basis of many electronic devices such as pn diodes. Further, customers must fully indemnify diodes incorporated and its. Now, if we join the two types of semiconductors ptype and ntype together then a new device is formed called as pn junction diode. A pn junction is the metallurgical boundary between the n and pregions of a semiconductor crystal.
We are not permitting internet traffic to byjus website from. In the case of normal diodes the diode damages at the break down voltage. In this paper formation a pn junction diode is explained by vlsi fabrication steps which are stated below. Abrupt depletion layer approximation let apply bias and calculate current through the pn junction currents in pn junction from sze, 1981. It has a particular voltage known as break down voltage, at which the diode break downs while reverse biased. A pn junction has rectifying currentvoltage iv or iv characteristics as shown in fig. 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.
The depletion region becomes smaller and the current ow becomes larger across the pnjunction. A pn junction diode is made by forming a ptype region of material directly next to a ntype region. A pn junction is a boundary or interface between two types of semiconductor materials, ptype and ntype, inside a single crystal of semiconductor. Diode is a basic element in electronic and digital circuit. Now lets try applying an external voltage to the pn junction diode. If positive terminal of dc source is connected to cathode and negative terminal is connected to anode, the diode is called reverse biased as shown in fig. The pn junction is a versatile element, which can be used as a. The diode is formed by joining both ntype and ptype semiconductors together. The conversion of alternating current into direct current is known as rectification. Reverse current can flow through the pn junction due to minority carriers. Since a junction forms between a p type and n type material it is called as pn junction. These types of diodes are commonly known as zener diodes and are discussed in a later tutorial.
Range of tunnel diode voltage for which the slope of the characteristics is ve is between v p and v v option c 11. P type and n type semiconductors, takenseparately are of very limited use. No generationrecombination in the depletion layer 6. The arrow direction in the diode symbol indicates a.
The pn junction diode is the typical diode that has been used in the previous circuits. Pdf defect analysis in semiconductor materials based on pn. 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 pn junction in the interface layer between the ptype and ntype material, a nonconducting layer called the depletion region occurs. A diode consists of a layer of ntype joined to a layer of ptype material creating a pn junction. Working of pn junction diode with biasing, characteristics.
Diode equationreverse breakdown and the zener diodetunnel. When the voltage applied is lower than the builtin voltage, the current is still nearly zero when the voltage exceeds the builtin voltage, the current can flow through the pn junction diode current voltage iv characteristics semiconductor diode consists of a pn junction with two contacts attached to the p and n sides p n v 0 qv k. Explain the formation of potential barrier and depletion layer. A pn junction diode allows electric current when it is forward biased and blocks electric current when it is reverse biased. This device is a combination of ptype and ntype semiconductor material hence it is also known as pn junction diode a junction is formed between the ptype and ntype layers.
A pn junction is a junction formed by joining ptype and ntype semiconductors together in very close contact. Detail of diode ivcharacteristic in the breakdown regime. Request pdf the pn junction diode introductiondiode currentcontact. Pn junction diode baising and its vi characteristics. Pn junction diode is symbolically represented as shown in picture. There are more phenomena at work here than just diffusion. 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. Nov 03, 2005 lecture 16 the pn junction diode ii equivalent circuit model november 3, 2005 contents. Characteristics of pn junction when the diode is forward biased and the applied voltage is increased from zero hardly any current flows through the diode in beginning, because the external voltage is being oppose by the internal barrier voltage v b whose value is 0. The dependence of the hole and electron drift mobility on the dopant concentration is shown in figure 3. The more holes or free electrons there are, the more particles will diffuse across the junction. Abrupt depletion layer approximation let apply bias and calculate current through the pn junction currents in pn junction.
The terminal connected to player is called anode a and the terminal connected to nlayer is called cathode k fig. The term junction refers to the boundary interface where the two regions of the semiconductor meet. As a result of the eus general data protection regulation gdpr. The pn junction is the basic structure of solar cell, lightemitting diode, and diode laser, and is present in all types of transistors. A zener diode when reverse biased can either undergo avalanche break down or zener break down. If both pside and nside of the diode are lightly doped, depletion region at the junction widens. This is the basic construction of the pn junction diode. It is acting as normal diode while forward biasing.
Iv characteristics uwhenever an electron on the pside moves to the nside, it is replaced by an electron generated through one of the rg centers ohmic ohmic minority minority excess majority carriers alocal excess majority carriers alocal e e excess carriers move to the contact with a relaxation time. A semiconductor diode consists of an n material region and a p material region separated by a pn junction. Diode, the twoterminal electronic component that rectifies current in one direction, is among the simplest but most useful semiconductor devices 1234. The nonlinearity will force us to modify our approach to analyzing circuits. These diodes are the normal pn junction diodes, which allow current to flow through them in. The direction of arrow is the direction of conventional current flow under forward bias. It is the most essential and the basic building block of the electronic device. Pn junction diode free download as powerpoint presentation. Pdf chapter 1 semiconductor pn junction theory and. Silicon wafer cleaning rca process in the ic processing wafers it is necessary to maintain the purity and perfection of material. By exploring the electrical properties of silicon, it is possible to acquire an understanding of the inner workings of the pn junction. When the diode is in forward bias, or v d0 v, then the voltage drop.
Pn junctions consist of two semiconductor regions of opposite type. These diodes have a very accurate and specific reverse breakdown voltage. Volume ii 2nd edition modular series on solid state dev. Due to this characteristic, the diode finds number of applications as given below. Schematic symbol for a pn junction diode p n representative structure for a pn junction diode zener diodes. Pn junction diode lecture2 outline about pn diode pn junction formation pn junction realization barrier height thermal equilibrium equilibrium depletion approximation abrupt junction pn junction bias. Diode iv characteristics our goal is to find out the currentvoltage characteristics of the. Reverse bias prevents current flow through a pn junction.
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