... P-N Junction Diode Formation ,Work & Its Characteristics. A P-N junction diode is a combination of two semiconductor materials, one is P-type semiconductor and another is N-type semiconductor. So we can say the concentration of free electrons (n) and donor ions ND are the same and similarly, the concentration of holes (p) and acceptor ions (NA) are the same. This allows electrical current to pass through the junction only in one direction. The right side of this graph is forward voltage region and a diode is in forward biased. Figure 1.1 illustrates the characteristics of a silicon junction … In a P-N junction Diode, we will consider the p-n junction with a forward-bias voltage employed. Understand the Working of PN Junction Diode. PN junction diode is one of the fundamental elements in electronics. Understand the V-I Characteristics of PN Junction Diode. The V-I characteristics of a diode can be forward or reverse. An ammeter is connected in series and voltmeter in parallel, while the supply is controlled through a variable resistor. PN junction is formed by bringing a P type material in contact with N type material. i.e., it is not a perfect diode. This region is highly resistive because of depletion of free charge carriers in this region. After this recombination process, there is a lack of or depletion of charge carriers (free electrons and holes) across the junction. admin 09/01/2021 10 0. One of the most common applications of the diode is the pn junction. It is acting as normal diode while forward biasing. When we do not apply any voltage across the PN diode, free electrons will diffuse through the junction to P side and holes will diffuse through the junction to N side and they combine with each other. Depletion layer opposes only the the majority carrier not minority carrier. The electric filed opposes further diffusion of free electrons from the n-type side and holes from the p-type side of the PN junction diode. Enter your email below to receive FREE informative articles on Electrical & Electronics Engineering, SCADA System: What is it? Fig.1 Reverse bias characteristics The junction is said to be reverse biased when the p-section of the diode is connected to the negative terminal of the battery and the n-se… Thus the acceptor atoms in the p-side near the junction edge and donor atoms in n-side near junction edge become negative and positive ions respectively. Biasing means applying external voltages to the device, biasing of a diode is of two types: Forward Biasing and other one is Reverse Biasing. When the forward-bias voltage is increased to a value where the voltage across the diode reaches approximately 0.7 V (barrier potential), the forward current begins to increase rapidly, as illustrated in Figure given below. Let us also assume that all the donor atoms have donated free electrons and become positive donor ions and all the acceptor atoms have accepted electrons and created corresponding holes and become negative acceptor ions. A junction is formed between the P-type and … The most basic device is diode.Diode is a two terminal PN junction device. It conducts current linearly with increase in voltage applied across the 2 terminals (provided the applied voltage crosses barrier potential). That means diffusion potential prevents charge carriers to cross the junction. This is referred to as the p-n junction diode. A P-N Junction Diode is one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. The LED uses GaAs, GaAsP or GaP material. The slope of the forward characteristic of a PN junction diode will become very steep quickly. Normally the voltage is taken along the x-axis and current along y-axis. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. An illustration of what happens when a PN junction diode is reverse-biased is shown below. The region across the junction where the free charge carriers get depleted is called depletion region. The width of the depletion region depends on the applied bias voltage. The PN junction diode silicon or germanium material. Volt-ampere characteristics of diode in forward bias condition.2. Hence, in absence of potential barrier across the junction in the forward bias condition free electrons enter into the p-type region and holes enter into the n-type region, where they recombine and release a photon at each recombination. In the Forward Bias, the diode allows the current to flow in uni-direction. Introduction: A PN junction diode is an electronic component that allows the flow of electric current only in one direction. For which it is used in the rectification … It’s made up from a small piece of semiconductor material (usually Silicon), it allows the electric current to flow in one direction while opposes the current in other direction. When a PN-junction diode is connected in a forward bias by giving a positive voltage to the P-type material and a negative voltage to the N-type terminal. The diode has two terminals, P-type semiconductor is called anode and N-type semiconductor is called cathode. A P-N junction diode is a piece of silicon that has two terminals. But when V exceeds VTH, the current suddenly becomes very high. When the P-type semiconductor material is joined with the N-type semiconductor material, a P-N Junction is formed, hence resulting P-N Junction is also called as a P-N Junction Diode. Let us consider a pn junction with a donor concentration ND and acceptor concentration NA. The relation between the width of the depletion region and bias voltage can be represented by an equation called Poisson Equation. The Volt-Ampere or V-I characteristics of a p-n junction diode is basically the curve between voltage across the junction and the circuit current. During the operation, when the diode is in forward biased condition, at some particular voltage, the potential barrier gets eliminated. PN Junction Diode in forwarding Bias. This external bias voltage is designated as V(bias). It is represented as a graph. When V is negative and less than VTH, the current is minimal. Across the pn junction, the free electrons donated by donor atoms in n-type side diffuse to the p-typer side and recombine with holes. A p-n junction formed by the doping f p-type and n-type material on a single crystal. VI Characteristic of PN Junction Diode. If we apply a reverse bias voltage to the diode, the depletion width increases and no charge can flow across the junction. For a typical junction diode, characteristics are shown in Figure. It is also called as simply P-N junction or semiconductor diode. When a forward-bias voltage is applied across a diode, there is current. The existence of negative ions in the p-type side along the junction and positive ions in the n-type side along the junction edge creates an electric field. So, on an application of a forward bias voltage the width of the depletion region i.e. It is a relationship between the current through the diode and applied voltage. Your email address will not be published. When the P-type material is connected with a positive terminal of battery it transfers the holes (positive charge carrier), which travels from p-type material to the N-type material through (Junction). PN junction Diode plays a vital role in our electronic fields, because of their unique property (current flows in only one direction) they are used in many electronic or electrical circuits like rectifiers, switches, clippers, clampers, voltage multipliers. In this configuration Diode allows the current to flow in uni-direction. The P-N junction is the basic element for semiconductor diodes. The horizontal line in the below figure represents the amount of voltage applied across the p-n junction diode whereas the vertical line represents the amount of current flows in the p-n junction diode. PN Junction Diodes are mostly used for rectification (Alternative Current to Pulsating DC). These free electrons are attracted towards the positive terminal of the diode while the holes are attracted towards the negative terminal of a diode. Reverse bias is the condition that essentially prevents current through the PN junction diode. A PN junction diode is a two-terminal electronics element, which can be classified as either ‘step graded’ or ‘linear graded’. This results in an increase in the depletion region. note that the depletion region is shown much wider than in forward bias. PN junction diode shows zero resistance in the forward direction and infinite resistance in the reverse direction. It is drawn to know the behavior of diode in the electrical circuit. But in a linearly graded junction, the doping concentration varies almost linearly with the distance from the junction. A limiting resistor is shown although it is not important in reverse bias because there is essentially no current. The volt-ampere characteristic of the PN-junction diode is a curve between the voltage over the junction and the circuit current. So that’s the forward bias characteristics of a pn junction diode. The forward characteristic of a PN junction diode is non linear, i.e., not a straight line. Is is reverse saturation current, e = charge of electron, k is Boltzmann constant and T is temperature in Kelvin scale. For Silicon diode VTH = 0.6 V. At a reverse voltage corresponding to the point P, there is abrupt increment in reverse current. PN junction diodes can be obtained in a number of semiconductor materials - the earliest diodes tended to be made from germanium, but most of them today are silicon diodes. The PN junction diode cannot emit light. When the P-type material is connected with a negative terminal of a battery, the holes are attracted away from the junction and attracted to the negative electrodes of batter. When P and N semiconductors are joined to make the PN junction semiconductor diode, the electrons near the PN junction jump from N to P and holes near the junction jump from P to N. This phenomenon creates a depletion layer.. Do check out – Diode Application in Clamper Circuit In this practical we will learn to obtain and draw the graph of V-I characteristic of a PN junction diode. Due to the absence of free charge carriers (free electrons and holes), the donor ions of n-type side and acceptor ions of p-type side across the junction become uncovered. PN junction diode and diode characteristics curve In: Principles. PN Junction Diode VI Characteristics. This current is called the forward current. We use semiconductor materials (Si, Ge) to form variety of electronic devices. They are used as clipper to clip the portion of AC. A PN Junction Diode is a two-terminal semiconductor device. Combine the curve for both forward bias and reverse bias, and you have the complete V-I characteristic curve for a PN junction diode, as shown in Figure give below. Before using this diode, it is necessary to know a little about its characteristics and properties with forward bias and reverse bias. The current through the PN junction is expressed as Here, voltage V is applied across the pn junction and total current I, flows through the pn junction. PN junction diode is one of the fundamental elements in electronics. This portion of the characteristics is known as breakdown region. In this article, we will focus on the i-vcharacteristics of the junction diode, specifically the pn junction. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. The graph below shows the current-voltage characteristic of a PN junction diode.When, V is positive the junction is forward biased, and when V is negative, the junction is reverse biased. In this article, we will learn about what is a PN Junction Diode and how it Works and also effect on PN Junction diode with different modes and I am sure this article will help you a lot to understand about Diode. 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