A P-N junction diode is a piece of silicon that has two terminals. Introduction: A PN junction diode is an electronic component that allows the flow of electric current only in one direction. 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. 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 results in an increase in the depletion region. 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. This portion of the characteristics is known as breakdown region. The potential barrier of this p-n junction is reduced when a forward-bias voltage is applied to it. When a P-type material is brought in contact with N- type material electrons and holes start recombining near the junction. As you have learned, forward bias produces the current through a PN junction diode and reverse bias essentially prevents current, except for a negligible reverse current. That means diffusion potential prevents charge carriers to cross the junction. The voltage VTH is known as the threshold or cut in voltage. A junction is formed between the P-type and … The voltage source is connected in such a way that it produces a Forward Bias. In Analog Electronics, Diode, Electronics. A p-n junction formed by the doping f p-type and n-type material on a single crystal. For More Read: Forward Bias of PN Junction [in Detail]. It generally shows the relation between bias voltage and current of a diode. Here, we have ignored the holes and free electrons created in the semiconductors due to unintentional impurities and defects. After completing this article you will be able to: A  PN Junction Diode is a two-terminal semiconductor device. 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. In this configuration Diode allows the current to flow in uni-direction. A second requirement is that the bias voltage, V(bias), must be greater than the barrier potential. The diode starts conducting at 0.7 volts and current through the diode increases linearly with increase in voltage. 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. Similarly, the holes created by acceptor atoms in p-type side diffuse to the n-type side and recombine with free electrons. An ammeter is connected in series and voltmeter in parallel, while the supply is controlled through a variable resistor. They are used as clamper to change the reference 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. ... P-N Junction Diode Formation ,Work & Its Characteristics. Understand the Working of PN Junction Diode. Is is reverse saturation current, e = charge of electron, k is Boltzmann constant and T is temperature in Kelvin scale. Such a voltage is called as Cut-off Voltage or Knee Voltage. So, on an application of a forward bias voltage the width of the depletion region i.e. interface or a boundary between two semiconductor material types Note: if the reverse bias voltage is increased up to a high value, it will damage the PN junction diode. It conducts current linearly with increase in voltage applied across the 2 terminals (provided the applied voltage crosses barrier potential). This is referred to as the p-n junction diode. That means if the positive side of the battery is connected to the p-side, then the depletion regions width decreases and carriers (holes and free electrons) flow across the 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. After this recombination process, there is a lack of or depletion of charge carriers (free electrons and holes) across the junction. 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. We call this region across the junction where the uncovered charges (ions) exist, as depletion region. PN junction diode is one of the fundamental elements in electronics. 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. If, we apply forward bias voltage to the p-n junction diode. 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. In the Forward Bias, the diode allows the current to flow in uni-direction. This is one requirement for forward bias. This region is highly resistive because of depletion of free charge carriers in this region. Figure 1.1 illustrates the characteristics of a silicon junction … Electrical4U is dedicated to the teaching and sharing of all things related to electrical and electronics engineering. 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. An illustration of what happens when a PN junction diode is reverse-biased is shown below. Fig.1 As we know the N-type material is consist of Electrons and the P-type material is consist of Holes. The diode has two terminals, P-type semiconductor is called anode and N-type semiconductor is called cathode. 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. The resistor limits the forward current to a value that will not damage the diode. Reverse bias is the condition that essentially prevents current through the PN junction diode. It is a relationship between the current through the diode and applied voltage. As you continue to increase the forward-bias voltage, the current continues to increase very rapidly, but the voltage across the diode is constant till 0.7v for silicon and 0.3v for germinium. In this article, we will focus on the i-vcharacteristics of the junction diode, specifically the pn junction. 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 basic device formed from this p-n junction is of two terminals. 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. So that’s the forward bias characteristics of a pn junction diode. The X-axis represents a voltage and Y-axis represents the current through the diode. The PN junction diode silicon or germanium material. During the operation, when the diode is in forward biased condition, at some particular voltage, the potential barrier gets eliminated. 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. This type of forward characteristic shows that resistance is not constant during the operation of the PN junction. 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. If the forward voltage exceeds beyond the limit, the forward current rises up exponentially and if this is done f… PN Junction Diode, its Characteristics and Applications, V-I CHARACTERISTIC OF A PN junction DIODE. The forward characteristic of a PN junction diode is non linear, i.e., not a straight line. 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. 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. When V is negative and less than VTH, the current is minimal. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. For which it is used in the rectification … 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. A Practical circuit arrangement for a PN junction diode is as shown in the following figure. VI Characteristic of PN Junction Diode. When a forward-bias voltage is applied across a diode, there is current. This device is a combination of P-type and N-type semiconductor material hence it is also known as PN Junction 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. Your email address will not be published. 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. 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. Characteristics of a p-n junction diode. 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). A PN junction diode is a two-terminal electronics element, which can be classified as either ‘step graded’ or ‘linear graded’. 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. admin 09/01/2021 10 0. It is represented as a graph. The V-I characteristics or voltage-current characteristics of the p-n junction diode is shown in the below figure. The PN junction region of a Junction Diode has the following important characteristics: Semiconductors contain two types of mobile charge carriers, “Holes” and “Electrons”. Semiconductor PN Junction Diode is the simplest semiconductor device. Understand the Effect of Forward Bias and Reverse Bias on PN Junction 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. Fig.1. 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). Your email address will not be published. PN junction diode shows zero resistance in the forward direction and infinite resistance in the reverse direction. 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. 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. In this type of diode, we dope one side of a semiconductor piece with an acceptor impurity and another side with a donor impurity. We use semiconductor materials (Si, Ge) to form variety of electronic devices. Volt-ampere characteristics of diode in forward bias condition.2. They are used as switches in many electronic circuitry. Let us consider a pn junction with a donor concentration ND and acceptor concentration NA. The region across the junction where the free charge carriers get depleted is called depletion region. In the Forward Bias, the … For Silicon diode VTH = 0.6 V. At a reverse voltage corresponding to the point P, there is abrupt increment in reverse current. One of the most common applications of the diode is the pn junction. This allows electrical current to pass through the junction only in one direction. i.e., it is not a perfect diode. Now we will examine the relationship between the voltage and the current in a diode on a graphical basis. PN junction is formed by bringing a P type material in contact with N type material. 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. Here, ε is the permittivity of the semiconductor and V is the biasing voltage. Usually voltage is taken across x-axis and current along y-axis. 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. 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. In a P-N junction Diode, we will consider the p-n junction with a forward-bias voltage employed. A PN junction diode is a two-terminal electronics element, which can be classified as either ‘step graded’ or ‘linear graded’. 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. The width of the depletion region depends on the applied bias voltage. Hey Swetha, Thanks for your comment, Keep visiting Studentsheart.com for best information! In this configuration, diode does not allow the flow of current. But in a linearly graded junction, the doping concentration varies almost linearly with the distance from the junction. 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. Forward bias is the condition that allows current through the PN junction Diode. Understand the V-I Characteristics of PN Junction Diode. 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. note that the depletion region is shown much wider than in forward bias. A diode connected for reverse bias. The V-I characteristics of a diode can be forward or reverse. The circuit arrangement of the curve is shown in the figure below. It is a basic semiconductor device that allows the flow of current in a unified direction. July 15, 2019. 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… The most basic device is diode.Diode is a two terminal PN junction device. In the case of normal diodes the diode damages at the break down voltage. For Si diode, at 0.7 V the current increases suddenly. If we apply a reverse bias voltage to the diode, the depletion width increases and no charge can flow across the junction. It will allow e- and hole to leak through the space charge region. This external bias voltage is designated as V(bias). Note that the -ve side of VBIAS is connected to the n-region of the diode and the +ve side is connected to the p-region.

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