The holes diffuse through the junction from higher concentration region (p-region) to lower concert region (n-region). When, V is positive the junction is forward biased, and when V is negative, the junction is reverse biased. A zener diode when reverse biased can either undergo avalanche break down or zener break down. V-I Characteristics, Working &Why is Zener Diode used a voltage regulator? But when V exceeds V TH, the current suddenly becomes very high. Physics practical to study about PN junction diode and obtain its V-I (voltage, current) characteristics until breakdown voltage and plot graph with diagram. We have seen the characteristics of pn junction diode through its graph. And Its Types, Explain the working of a junction diode as (i) half wave rectifier and (ii) full wave rectifier. Therefore, the circuit current is zero at V=0 V, as indicated by point O in figure below. Fig.1: Circuit Connection for V-I characteristics of a pn junction. What is a Diode and How does it Work. Enable registration in settings - general, P-N Junction Diode Formation ,Work & Its Characteristics| Electronics Tutorial |, Semiconductor diode or p-n junction diode, Working of p-n junction diode under forward bias, Working Of p-n junction diode under Reverse bias, Static and Dynamic resistances of a Junction Diode, Explain reverse biasing in a p-n junction diode, Explain forward biasing in a p-n junction diode, explain the V-I characteristics of a p-n junction diode in forward biasing and in reverse biasing, What is junction barrier or potential barrier, What is a Photodiode, LEDs, Solar Cells & Opto Electronic Devices | Electronics Tutorial |. Similarly, a p-n junction can be made by fusing a small quantity of pentavalent impurity into a p-type semiconductor, p-n junction can be obtained when p-type semiconductor is heated in phosphorus gas to result into diffused n-type layer on the semiconductor (Figure 3). It allows the current to flows both in the forward as well as in the reversed direction, when the Zener voltage is reached. The V-I characteristics or voltage-current characteristics of the p-n junction diode is shown in the below figure.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. A zener diode when forward biased behaves like an ordinary P-N junction diode. The variation of current with the applied voltage across the junction diode gives the characteristics of p-n junction diode. Avalanche break down:-If both p-side and n-side of the diode are lightly doped, depletion region at the junction widens. Effect of temperature on V I characteristics The effect of increased temperature on the characteristics curve of a PN junction diode is as shown in above figure. Doping can occur in a semiconductor utilizing donor impurities like antimony, and this is called N-type doping. One of the most common applications of the diode is the pn junction. The graph below shows the current-voltage characteristic of a PN junction diode. This potential difference reduces the potential barrier (Vb). The crossed over electrons in p region and holes in n region are in fact minority carriers so this process of cross over is called minority carrier injection. Indicate the differences between the characteristics of silicon and germanium diodes and state approximately their cut-in voltages. admin 09/01/2021 10 0. A p-n junction when not connected to a cell or battery is shown in figure 9(A). It is a special type of diode which operates in the breakdown region. What is a rectifier ? The effective potential barrier reduces to (Vb – V) and the thíckness of the depletion layer also decreases (Figure 8(B)) The junction resistance becomes very low. PN junction diode is a two terminal device, the characteristics of diode depends on the polarity of the external potential applied to the PN junction diode. This type of forward characteristic shows that resistance is not constant during the operation of the PN junction. A semiconductor may … Related Post: Thyristor & Silicon Controlled Rectifier (SCR) Non Ideal PN Junction  Real diode characteristics V A high level injection recombination at depletion ideal resistive log(I) •At low current, the measured current is larger than the ideal current •When the bias voltage increase to close to V Bi, the diode current, the current increase is slowed down Mansunansun Semiconductor diode consists of a p-n junction having metallic contacts at both the ends as shown in figure 7(A). D.C. or Static resistance of the diode is defined as the ratio of the d.c. voltage across the diode to the direct current flowing through it. This results in reduced potential barrier. a forward potential difference of V volt is applied across the diode. Concentration of injected holes in n-side and that of injected electrons in p side increases a lot near the junction that ends. VOLTAGE-CURRENT CHARACTERISTICS OF A PN JUNCTION DIODE Conclusions: (a) V-I graph for diode is not a straight line passing through the origin. But on the condition of the applied voltage, the biasing conditions are … When holes diffuse through the junction, the p-region near the junction is left with negative ions (or acceptor ions) which remain fixed in their positions in the crystal lattice. That is, holes diffuse through the junction from p-region to n- region and combine with electrons in the n-region and hence get neutralized. It will allow e- and hole to leak through the space charge region. This potential difference is called potential barrier generally represented as Vb. Simulation using Multisim of PN Junction Diode Characteristics. The Zener diode is made up of silicon material. (1), it is a two-terminal device where the terminal A stands for … 2. As a result of this, large electron-hole pairs are produced which diffuse through the junction and hence there is a sudden rise in the reverse current (figure 13). Diode is a two terminal PN junction device. The electric field exerts force on electrons in p-region to move towards n-side and also exerts force on holes in n-region to move towards p-side, Thus, a drift current begins to flow due to the drifting of holes and electrons across the junction. The circuit connection for determining the V-I characteristics of a pn junction is shown in the figure below. PN Junction Diode VI Characteristics in Reverse Bias Therefore, this is all about PN junction diode in zero bias, forward bias and reverse bias conditions and VI characteristics of PN junction diode. In this article, we will focus on the i-vcharacteristics of the junction diode, specifically the pn junction. The drifting continues till drift current becomes equal to the diffusion current. The depletion layer contains positive and negative immobile ions on either side of the p-n junction. On the other hand, when electrons diffuse through the junction, the n-region near the junction is left with positive ions (or donor or) fixed in their positions in the crystal lattice. When V is negative and less than V TH, the current is minimal. Pn junction diode is one of the most basic diodes. These are the easiest and basic diodes available in and use PN junction characteristics like depletion layer, diffusion and drift current. 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 trivalent impurity .p-n junction (Figure 1). P-N Junction Diode Theory A diode has two regions that are p-type and n-type where it is operated. A p-n junction diode when not connected to a cell or battery is shown in figure 8(A). The positive and negative ions set up a potential difference across the p-n junction which opposes the further diffusion of electrons and holes through the junction. It may be noted that the forward characteristics shifts upwards with increase in temperature. Form this instant, the current increases with the increase in forward voltage. Hence, the junction resistance becomes very high and as a result practically no current flows through the circuit. How is junction barrier formed across a p-n junction ? Observe the different quasi Fermi levels for conduction band and valence band in n and p regions (red curves). 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. This current can be effectively ignored as long as the reverse breakdown voltage of the diode is not exceeded. 2. This electric field is directed from positive charge to negative charge across the junction. (b) The resistance across the junction of a diode in large below the knee voltage . It is drawn to know the behavior of diode in the electrical circuit. It allows the flow of electric current only in forward biased condition, in the reverse-biased it blocks the flow of electric current. V-I Characteristics of PN Junction Diode. When a cell or a battery is connected across the p-n junction diode such that positive terminal is connected to p-region and negative terminal is connected to n-region (figure 8(b)]. We have also learned about diffusion current, depletion region, drift current and barrier potential. If the reverse bias in increased to a high value, the covalent bonds near the junction break down and a large number of electron-hole pairs are liberated. This current is not affected by the increase in applied voltage but increases with the increase in temperature. 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