characteristics of pn junction diode

An ammeter is connected in series and voltmeter in parallel, while the supply is controlled through a variable resistor. With an increase in the voltage, the current also increases. Normally the voltage is taken along the x-axis and current along y-axis. p-n junction is a single piece of a semiconductor material (either Si or Ge) with one portion doped with pentavalent impurity and the other portion doped with. The "p" side contains an excess of holes, while the "n" side contains an excess of electrons in the outer shells of the electrically neutral atoms there. Depletion region created across the pn junction by the initial movement of majority carrier across the junction. 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. As a result, there will be a forward current flowing through the diode. The right side of this graph is forward voltage region and a diode is in forward biased. The diode has two terminals, P-type semiconductor is called anode and N-type semiconductor is called cathode. Let us consider a pn junction with a donor concentration ND and acceptor concentration NA. In this configuration, diode does not allow the flow of current. The forward characteristic of a PN junction diode is non linear, i.e., not a straight line. Electrical4U is dedicated to the teaching and sharing of all things related to electrical and electronics engineering. So, on an application of a forward bias voltage the width of the depletion region i.e. In this configuration Diode allows the current to flow in uni-direction. A PN Junction Diode is a two-terminal semiconductor device. The width of the depletion region depends on the applied bias voltage. Understand the Practical Applications of PN Junction Diode. One of the terminals is doped with P-type material and the other with N-type material. 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. As mentioned above if we connect -ve terminal of the battery to P-type material and +ve Terminal of Battery to N-type material this lead to the diode in Reverse Bias. 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). When a forward-bias voltage is applied across a diode, there is current. 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. It is drawn to know the behavior of diode in the electrical circuit. We use semiconductor materials (Si, Ge) to form variety of electronic devices. V-I Characteristics of PN Junction Diode Volt-ampere (V-I) characteristics of a pn junction or semiconductor diode is the curve between voltage across the junction and the current through the circuit. In the Forward Bias, the diode allows the current to flow in uni-direction. After completing this article you will be able to: A  PN Junction Diode is a two-terminal semiconductor device. Understand the V-I Characteristics of PN Junction Diode. They are used as clipper to clip the portion of AC. Zener diode is a P-N junction diode specially designed to operate in the reverse biased mode. Note: if the reverse bias voltage is increased up to a high value, it will damage the PN junction diode. Characteristics of PN junction diode is a graph between the voltage applied across its terminals and the current that flows through it. Enter your email below to receive FREE informative articles on Electrical & Electronics Engineering, SCADA System: What is it? In Analog Electronics, Diode, Electronics. 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. The V-I characteristics or voltage-current characteristics of the p-n junction diode is shown in the below figure. Understand the Effect of Forward Bias and Reverse Bias on PN Junction Diode. note that the depletion region is shown much wider than in forward bias. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage as the diode has an exponential current-voltage (I-V) relationship. Similarly, the holes created by acceptor atoms in p-type side diffuse to the n-type side and recombine with free electrons. 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. This is one requirement for forward bias. V-I characteristics of p-n junction diode. A P-N junction diode is a combination of two semiconductor materials, one is P-type semiconductor and another is N-type semiconductor. One terminal of p-n junction diode is Anode and other is cathode. A PN Junction Diode is a semiconductor device with two opposite region such as (P-type region and N-type region). A PN junction diode is a two-terminal electronics element, which can be classified as either ‘step graded’ or ‘linear graded’. For which it is used in the rectification … This type of forward characteristic shows that resistance is not constant during the operation of the PN junction. 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. For Silicon diode VTH = 0.6 V. At a reverse voltage corresponding to the point P, there is abrupt increment in reverse current. This results in an increase in the depletion region. For More Read: Forward Bias of PN Junction [in Detail]. The most basic device is diode.Diode is a two terminal PN junction device. Here, we have ignored the holes and free electrons created in the semiconductors due to unintentional impurities and defects. Usually voltage is taken across x-axis and current along y-axis. Hey Swetha, Thanks for your comment, Keep visiting Studentsheart.com for best information! As we know the N-type material is consist of Electrons and the P-type material is consist of Holes. This is referred to as the p-n junction diode. Analog Electronics: V-I Characteristics of PN Junction DiodeTopics Covered:1. The potential developed across the junction due to this space charge is called the diffusion voltage. In this article, we will focus on the i-vcharacteristics of the junction diode, specifically the pn junction. A Barrier Potential is an internal potential a semiconductor material, in case of Silicon-based PN Junction diode it is 0.7v and in case of Germanium, it is 0.3v. PN junction is formed by bringing a P type material in contact with N type material. The X-axis represents a voltage and Y-axis represents the current through the diode. 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. 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. Fig.1 Your email address will not be published. It is a basic semiconductor device that allows the flow of current in a unified direction. A diode connected for reverse bias. 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. This external bias voltage is designated as V(bias). For Si diode, at 0.7 V the current increases suddenly. PN junction diode is one of the fundamental elements in electronics. 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. On the other hand, when the diode is reverse biased it opposes the electric current to flow. Forward Biasing of Diode: We connect positive terminal of the battery to the P-type Material and Negative terminal of the battery to the N-type, hence this configuration is called as Forward Bias Configuration of Diode. As more of the n- region and p-regions become depleted of majority carriers, the high potential barrier is created thus opposing electric current to flow in reverse bias. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. 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. The diffusion voltage across a pn junction diode can be expressed as The diffusion potential creates a potential barrier for further migration of free electrons from n-type side to p-type side and holes from p-type side to n-type side. The potential barrier of this p-n junction is reduced when a forward-bias voltage is applied to it. So that’s the forward bias characteristics of a pn junction diode. If the forward voltage exceeds beyond the limit, the forward current rises up exponentially and if this is done f… Fig.1. This region is highly resistive because of depletion of free charge carriers in this region. The basic device formed from this p-n junction is of two terminals. admin 09/01/2021 10 0. i.e., it is not a perfect diode. It is also called as simply P-N junction or semiconductor diode. These free electrons are attracted towards the positive terminal of the diode while the holes are attracted towards the negative terminal of a diode. These positive uncovered donor ions towards n-type side adjacent to the junction and negative uncovered acceptors ions towards p-type side adjacent to the junction cause a space charge across the pn junction. The voltage VTH is known as the threshold or cut in voltage. 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 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. A second requirement is that the bias voltage, V(bias), must be greater than the barrier potential. PN junction diode shows zero resistance in the forward direction and infinite resistance in the reverse direction. Introduction: A PN junction diode is an electronic component that allows the flow of electric current only in one direction. It means in order to forward bias the PN junction diode V(bias) should be greater than 0.7 for silicon and 0.3V for germanium. A p-n junction formed by the doping f p-type and n-type material on a single crystal. 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. A P-N junction diode is a piece of silicon that has two terminals. They are used as clamper to change the reference voltage. The region across the junction where the free charge carriers get depleted is called depletion region. Thanks and Stay connected with Studentsheart.com. In a step graded PN junction diode, the concentration of dopants both, in the N side and the P side are uniform up to the junction. Reverse bias prevents current as long as the reverse-bias voltage does not exceed the breakdown voltage limit of the junction. When V is negative and less than VTH, the current is minimal. 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. The diode is formed by joining both N-type and P-type semiconductors together. This allows electrical current to pass through the junction only in one direction. 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. An illustration of what happens when a PN junction diode is reverse-biased is shown below. PN junction diode and diode characteristics curve In: Principles. In the case of normal diodes the diode damages at the break down voltage. But when V exceeds VTH, the current suddenly becomes very high. There are Many different types of PN Junction Diode, and we have covered all of them check out the  working of different types of diodes: This is all about PN Junction Diode Working, Operations, and its V-I Characteristics if you like our article or you think you have learned from this PN Junction Diode, its V-I Characteristics please share and comment below. We call this region across the junction where the uncovered charges (ions) exist, as depletion region. interface or a boundary between two semiconductor material types Similary when the N-type material is connected with a positive terminal of a battery, the free electrons are attracted away from the junction and attracted towards the positive electrodes. A fundamental picture of what happens when a PN junction diode is forward-biased is shown below. The PN junction diode cannot emit light. Reverse Biasing of Diode: We connect Negative Terminal Battery to the P-type Material and Positive terminal of Battery to the N-type Material, hence this configuration is called as Reverse Bias configuration of Diode. They are used as switches in many electronic circuitry. Forward bias characteristics The junction is said to be forward biased when the p-section of the diode is connected to the positive terminal of the battery and the n-section of the diode is connected to the negative terminal of the battery. 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. A PN junction diode is a two-terminal electronics element, which can be classified as either ‘step graded’ or ‘linear graded’. Fig.1 shows the circuit arrangement for determining the V-I characteristics of a p-n junction diode. It generally shows the relation between bias voltage and current of a diode. The holes are positively charged while the electrons negatively charged. It is represented as a graph. When the N-type material is connected with a negative terminal of battery it transfers the free electrons (negatively charged carriers), which travels from n-type material to the P-type material through (junction). Your email address will not be published. The voltage source is connected in such a way that it produces a Forward Bias. After this recombination process, there is a lack of or depletion of charge carriers (free electrons and holes) across the junction. In a P-N junction Diode, we will consider the p-n junction with a forward-bias voltage employed. The volt-ampere characteristic of the PN-junction diode is a curve between the voltage over the junction and the circuit current. The basic diode structure and symbol of PN Junction Diode is shown in the figure below. They are used in Voltage Multipliers to increase the output voltage. 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. PN Junction Diodes are mostly used for rectification (Alternative Current to Pulsating DC). Forward bias is the condition that allows current through the PN junction Diode. In the Forward Bias, the … It shows how much current will flow for a particular value of diode voltage. 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. PN Junction Diode VI Characteristics. The circuit arrangement of the curve is shown in the figure below. 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