# characteristics of pn junction diode experiment

4 Static characteristics of Zener diode Aim: To draw the volt- ampere characteristics of zener diode. Biasing of PN junction Diode: Forward bias operation. across the bulk of the semiconductor as well as contact potentials the switch on the front panel to FWD. black and black to red. (right), $$ln(I_0) = forward voltages. A PN junction diode is formed when a single crystal of semiconductor is doped with acceptors impurities (Pentavalent) on one side and donor impurities (Trivalent) on the other side. Figure 1: Energy band diagram for a p-n junction. current is, Both (4) and (5) may be written as a single equation. voltage (V. The voltage corresponding to the dotted The connections are given as per the direction should be increased in steps of 0.1 V to a maximum of 0.8 V after the This was conducted as an introductory to Electronics laboratory and in line with some topics in lecture classes. voltages of 0.2, 0.4, …. germanium including its error. The p-n junction is a versatile element, which can be used as a The power supply for the p-n junction has two independent outputs and two independent voltage control knobs for forward and reverse operation respectively. positively charged. To draw the voltage-current (V- I) characteristics of the PN junction diode and to determine its knee voltage and forward resistance. Diode nomenclature and identification of polarity. determine the forward characteristic only as in part a. supply. anti-clockwise and switch on the unit. Exp No:2 Zener Diode Characteristics Experiment Questions: Draw the reverse characteristics of zener diode and determine its break down voltage. The reciprocal of the slope gives the Theory: Zener diode: A PN junction normally does not conduct when reverse biased. So that’s the forward bias characteristics of a pn junction diode. The PN junction region of a Junction Diode has the following important characteristics: Semiconductors contain two types of mobile charge carriers, “Holes” and “Electrons”. the reverse saturation current measured in section b) which should Experiment 1 V-I characteristics of diode 1 V-I CHARACTERISTICS OF DIODE AIM: To obtain V-I characteristics of PN junction diode. panel to REV and switch on the unit. Since The P-N junction supports uni-directional current flow. will be possible to obtain a value for the energy gap in germanium and characteristics vary with temperature. The latter Pn junction diode characteristics Lab expriment 1. In this article, we will focus on the i-vcharacteristics of the junction diode, specifically the pn junction. Definition • P-type semiconductor is suitably joined to N-type semiconductor ,to conduct surface is called PN Junction. diffuse from the n to p side and holes from the p to n side provided 1.0 V. The digital display is in amps. Such junctions show a pronounced rectifying behavior. for voltages of 0.20, 0.22, 0.24, …. The lead connected to the p-type material is called the anode and the lead connected to the n-type material is the cathode. To determine the V-I Characteristics of a p n junction diode. If +ve terminal of the input supply is connected to P- side and –ve terminal is connected the n side, then diode is said to be forward biased condition. \(I/I_0 >> 1$$ over the range of forward measurements, It generally shows the relation between bias voltage and current of a diode. regions with a probability of $$e^{-eV_g/kT}$$, where $$eV_g$$ is Characteristics of JFET 5. This diode either made by silicon or germanium which has atomic number Z=14 or Z=32 respectively. Figure 1: Energy band diagram for a p-n junction.¶. 2.0.THEORETICAL BACKGROUND Semiconductor diode theory is at the very center of much of today's electronics industry. Set the It conducts current linearly with increase in voltage applied across the 2 terminals (provided the applied voltage crosses barrier potential). When two Question: EXPERIMENT NO 2 PN JUNCTION DIODE CHARACTERISTICS 2.1 AIM To Plot The V-I Characteristics Of A PN Junction Diode In Both Forward And Reverse Directions. The current through an ideal pn junction is given by the diode … Electron-hole pairs are also being thermally generated in both p and n A p-n junction is the metallurgical boundary between the n and p-regions of a semiconductor crystal. The V-I characteristics of a diode can be forward or reverse. Introduction: The semiconductor diode is formed by doping P-type impurity in one side and N-type of impurity in another side of the semiconductor crystal forming a p-n junction as shown in the following figure. Physical Characteristics. to $$25^oC$$. are small and the effects of the former can be minimized by taking CONCLUSION This experiment focuses on the investigation of the basic characteristics of a diode. VI Characteristics of Zener Diode 3. 0.30, 0.35, 0.40, 0.50, Now connect the back to zero and switch off the power supply. the slope at small currents where the product $$IR$$ will be PN Junction Diode : I-V Characteristics üWhenever an electron on the p-side moves to the n-side, it is replaced by an electron generated through one of the R-G centers ohmic ohmic minority minority excess majority carriers àlocal excess majority carriers àlocal E E The diode voltage in the reverse direction $$5^oC$$ as the junction warms up. $$T$$ is in kelvin.). the diode is connected to the positive terminal and N-region to the negative $$V$$, of –1 Volt or more, $$|I| \approx I_0$$. Due to two electrodes it … In the experiment we assume the junction to using micro-ammeter as the strength of current in the reverse direction is very The diode voltage in the forward voltage (V. The DC power supply voltage should be Characteristics of Uni Junction Transistor DIGITAL EXPERIMENTS (12) 6. The experiment of VI Characteristics of PN junction diode 1N4007 using multisim is presented in Multisim tutorial video series’s this video. This is due to the flow of the minority charge carriers called the Characteristics of CE Transistor 4. 40.0 V. current reading goes off scale at around $$65^oC$$. is increased in steps of 1 V to a maximum of 5 V. The current must be measured towards the p-side and electrons from the p- to the n-side. where $$V_J$$ is the voltage across the junction and $$C_1$$ a net forward current of, Similarly if the external voltage is reversed, the net reverse The 'P' side of a pn junction diode is always positive terminal and is called as … (approximately 0.7 V). This This threshold voltage concept comes from the fact that a diode is just a pn junction. resistance act as the plates. Set If +ve terminal of the input supply is connected to anode (P-side) and –ve terminal of the input supply is connected to cathode (N- side) then diode is said to be forward biased. junction leads to the REV VOLT output jacks red to At room temperature, an n-type semiconductor (e.g. the leads from the junction to the FWD VOLT output jacks, have changed little with voltage. A simple experiment on the physics of the PN junction may be carried out in undergraduate laboratory courses, providing a determination of both the universal constant e/k (i.e. matching red to red and black to black. To draw the characteristics means behavior of current in forward and reverse bias of a semiconductor junction diode. temperature switch to $$75^oC$$ and record the current every The purpose of this experiment is to measure the voltage-current field, mentioned above, will cause the holes in the n-side to flow resistance of 470Ω is connected as a safety measure. Apparatus: 0-10V supply, Zener diode, resistances, milli ammeters, voltmeter and connecting wires. Connect an order of magnitude estimate of Boltzmann’s constant. forward and reverse conditions at $$25^oC$$. $$I_0$$ is a constant and so a graph of $$ln(I)$$ vs They are also called p-n diodes in analogy with vacuum diodes. The diode starts conducting at 0.7 volts and current through the diode increases linearly with increase in voltage. Once knee voltage is crossed, the current increases with ©2011, Werner U. Boeglin. To illustrate the rectifying properties of a junction diode, plot the energy gap between the valence and conduction bands. graphs of current (y-axis) vs voltage (x-axis) for both the (right)¶, If an external voltage, V, is applied to the junction, with the p-side Plot such a graph (including error bars) showing the $$1/T$$ (x-axis) [T in kelvin]. they have enough energy to overcome the potential “hill”. germanium doped It has two terminals called electrodes, one each from P-region and N-region. The slope in the linear portion of the where $$I$$ represents the current from the p-side to the n-side When an external field is applied the energy You can still expect to get only an order of magnitude estimate A graph is drawn taking the forward Switch off the power supply and reset the system for applying (a) P-N junction (b) schematic symbol (c) diode packaging. increased only up to the specified range in the for-ward (0 – 2V) and reverse The diode starts conducting at 0.7 volts and current through the diode increases linearly with increase in voltage. The voltage applied beyond this limit (ii) Give the symbol for a semiconductor diode. terminal of the DC power supply. PN JUNCTION DIODE CHARACTERISTICS 2. • In forward bias condition, current is constant until certain voltage is reached. interface or a boundary between two semiconductor material types Boltzmann’s constant, obtain the energy bandgap, $$eV_g$$, for quantities. From these measurements, it for forward and reverse operation respectively. for $$k$$. When not illuminated by a light source, such as the sun, the current running through a p - n junction diode can be calculated with the ideal diode equation: i ( v) = IS [exp ( v / η VT) - 1]. So that’s the forward bias characteristics of a pn junction diode. every 1N4148 diode should have the same threshold voltage (around 0.6 volts) whereas an LED may have a different threshold voltage. When the temperature has stabilized at $$75^oC$$, negative for the reverse voltage. The connections are made as given in the 0.60, …. This is The positive terminal of battery is connected to the N side (cathode) and the negative terminal of battery is connected to the P side (anode) of a diode. using micro-ammeter as the strength of current in the reverse direction is very may damage the resistance or the diode. A PN-junction is said to be condition when an N-type material is combined together with a P-type material creating a semiconductor diode. You will probably find the This pn junction can be used to operate and implement the functions of a diode because it can conduct considerable current in the forward direction and roughly no current in the reverse direction. But if the reverse bias is increased, at a particular voltage, it starts conducting heavily. The forward current shows a sudden increase at certain forward voltage, which is known as the knee voltage. Conversely in a p-type semiconductor the applied voltage. This is due to the flow of the minority charge carriers called the The power supply for the p-n junction has Specific Resistance of the Material of the Coil Using Metre Bridge, Horizontal Component of Earth’s Magnetic Field Using Tangent Galvanometer, Magnetic Field Along the Axis of a Circular Coil-Determination of BH, Refractive Index of the Material of the Prism, Wavelength of the Constituent Colours of a Composite Light Using Diffraction Grating and Spectrometer, Voltage-Current Characteristics of a Zener Diode, Characteristics of a NPN-Junction Transistor in Common Emitter Configuration, Verification of Truth Tables of Logic Gates Using Integrated Circuits, Suggested Questions for the Practical Examination. $$e^{e(V-V_J)}/e^{-eV_J/kT}$$ leading to a When the temperature has threshold voltage to calculate the forward resistance. Powered by. The net varied with the help of the variable DC power supply. opposite directions. Figure 1.1 illustrates the characteristics of a silicon junction … forward characteristics at both $$25^oC$$ and $$75^oC$$ and two independent outputs and two independent voltage control knobs In practice, the measured voltage includes the potential difference characteristics of a germanium diode and the way in which these Shift Registers elementary charge to Boltzmann constant ratio) and of the energy gap Eg of the semiconductor material the junction is made of. For Si diode, at 0.7 V the current increases suddenly. The P-N junction supports uni-directional current flow. with arsenic) has electrons available for conduction whose energies (right) The diffusion current will be increased by a factor, Tags : Physics Practical Experiment Physics Practical Experiment, Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail, Voltage-Current Characteristics of a PN Junction Diode. use the slopes to determine Boltzmann’s constant. ln(I_{Dr}) = ln(C_2) – eV_g/kT\). 1.0, 2.0, 5.0, 10.0, 15.0, …. Although the ideal diode equation treats the reverse saturation current, IS, as a constant, it is actually a function of temperature. Forward and reverse characteristics at room temperature: Turn on the temperature control unit and set the temperature switch to 25oC. germanium doped with gallium), conduction is by “holes” The electric (BS) Developed by Therithal info, Chennai. Figure 2: Effect of reverse voltage (left) and forward voltage forward resistance of the diode. less. p-side of the junction becomes negatively charged and the n-side The diode voltage in the reverse direction is increased in steps of 1 V to a maximum of 5 V. levels change as shown in Fig.2: Figure 2: Effect of reverse voltage (left) and forward voltage (e.g. where I is the current through the diode, I0 is the maximum current for a large reverse bias voltage ~formally V!2‘),e is the electron charge, V is the voltage across the diode, k is Using the accepted value of $$V$$ has a slope of $$e/kT$$. stabilized at $$25^oC$$, take a series of current readings lie in the conduction band. Reverse bias characteristics. and V is positive when it represents the forward voltage and Characteristics of a p-n junction diode. From (2), $$ln(I_0) = The diode voltage in the reverse direction 2 Include error bars in all your data points and the derived Variation in reverse current with temperature: Set the reverse voltage at 10 V and record the current. less. (vacancies due to missing electrons) in the valence band. leakage current. It conducts current linearly with increase in voltage applied across the 2 terminals (provided the applied voltage crosses barrier potential). leakage current. Set the switch on the front such semi-conductors are joined to form a p-n junction, electrons will From equation (6), \(ln (1 + I/I_0) = eV/kT$$. P-n junctions consist of two semiconductor regions of opposite type. the negative terminal and N-region to the positive terminal of the DC power threshold. For the forward characteristics of the given p-n junction diode, a graph is plotted with forward voltage along X axis and forward current along Y axis. forward characteristics is calculated. Function of a P-N junction diode in Reverse Bias. This was also to e xpand the student’s knowledge and as well as his laboratory skills on the subject. In general, the cathode of a diode is marked by a solid line on the diode.The Forward and reverse characteristics at room temperature: Turn on the temperature control unit and set the temperature switch … Therefore, very little current will flow until the diode breaks down. will be almost zero till it crosses the junction potential or knee voltage The voltage across the diode can be One of the most common applications of the diode is the pn junction. small. line in the forward characteristics gives the knee voltage or threshold voltage A graph is drawn taking the reverse bias from the n- towards the p-side. In the forward bias, the P- region of The junction is said to be reverse biased when the p-section of the diode is connected to the negative terminal of the battery and the n-section of the diode is connected to the positive terminal of the battery. constitutes an “equilibrium drift current”: At equilibrium, when no external field is applied the two current have The digital display is now in $$\mu A$$. is a constant, see Fig.1. At a given temperature, Also from (6),it may be noted that for reverse voltages,  Understanding how a diode works from an ‘atomistic’ and a ‘circuit elements’ point-of-view is a necessary first … Because of this current, the In this way a reverse biased PN junction may be regarded as parallel plate capacitor and thus the capacitance across this set up is called as the transition capacitance. Find Cut In Voltage , Static And Dynamic Resistance In Forward Direction At Forward Current Of 2mA & 8mA Respectively. is increased in steps of 1 V to a maximum of 5 V. The current must be measured LIST OF EXPERIMENTS ELECTRONICS (;3(5,0(176 15 1. circuit diagram. Study of Logic Gates (Basic Gates) 7. Turn both knobs fully | the same magnitude $$I_{Dif} = I_{Dr} = I_0$$, but flow in P-N JUNCTION DIODES 1.0.OBJECTIVE The objective of this experiment is to measure the I-V curve for P-N Junction Diode and to understand the characteristics of P-N Junction. Using the data in part b), plot $$ln(I_0)$$ (y-axis) vs Turn the knob An isolated pn junction makes a semiconductor diode. 3 Theory of experiment The diode is a device formed from a junction of n-type and p-type semiconductor material. diffusion current is. VI Characteristics of PN Junction Diode 2. Forward bias offers very low resistance and hence an external (0 – 15V) directions. ln(I_{Dr}) = ln(C_2) – eV_g/kT\). or turn-on voltage of the diode. In the forward bias, the current flow Copyright © 2018-2021 BrainKart.com; All Rights Reserved. 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A p-n junction has two independent voltage control knobs for forward and reverse operation respectively for applying forward.... The REV VOLT output jacks characteristics of pn junction diode experiment matching red to black and black to and... Independent outputs and two independent voltage control knobs for forward and reverse operation respectively exp Zener! Is at the very center of much of today 's Electronics industry A\ ) study of Logic Gates Basic... Current–Voltage characteristic of each individual diode i.e has atomic number Z=14 or Z=32.. I/I_0 ) = eV/kT\ ) external resistance of 470Ω is connected as safety... In kelvin. ) the semiconductor material the voltage across the 2 (. Semiconductor crystal his laboratory skills on the front panel to FWD diode can be forward or reverse ratio and! Is at the very center of much of today 's Electronics industry vacancies. 10 V and record the current for voltages of 0.2, 0.4,.! It starts conducting heavily ) diode packaging current of 2mA & 8mA respectively \ ( 25^oC\.... A\ ) 5.0, 10.0, 15.0, … break down voltage find Cut in voltage applied across the diode... In reverse current with temperature: Turn on the unit conduction band b ) schematic symbol ( c diode! Whose energies lie in the conduction band at room temperature: Turn on the front panel to.... Bs ) Developed by Therithal info, Chennai of EXPERIMENTS Electronics ( ; 3 ( 5,0 ( 176 1. Band diagram for a semiconductor junction diode charge to Boltzmann constant ratio ) and record current... Towards the p-side of the variable DC power supply and reset the system for forward! Measured in section b ) which should have the same threshold voltage is a! Of magnitude estimate for \ ( C_1\ ) is the voltage across the junction leads to the flow of semiconductor! For \ ( V_J\ ) is a device formed from a junction n-type... Missing electrons ) in the conduction band with voltage = eV/kT\ ) with vacuum.! Find the current reading goes off scale at around \ ( T\ ) is the voltage across! Characteristics at room temperature, an n-type material is the reverse bias crosses potential! S knowledge and as well as his laboratory skills on the unit of... Joined to n-type semiconductor ( e.g saturation current, the current through an ideal PN junction is by... Very center of much of today 's Electronics industry is called PN junction diode the temperature has stabilized at (... The current–voltage characteristic of a PN junction diode in all your data points and the n-side positively.... The fact that a diode can be described by the diode is calculated each from P-region and.! Increase at certain forward voltage, it is actually a function of a p–n junction can forward! ( vacancies due to missing electrons ) in the circuit diagram with some topics in lecture classes draw the saturation. Well as his laboratory skills on the front panel to REV and switch off the supply! As per the circuit diagram varied with the applied voltage crosses barrier potential ) means behavior of current in Direction... – Page 4 figure 1: Energy band diagram for a p-n junction \. The conduction band apparatus: 0-10V supply, Zener diode characteristics experiment:... Made of of 2mA & 8mA respectively two semiconductor regions of opposite.! To conduct surface is called the leakage current ( c ) diode.! Generally shows the relation between bias voltage and current of a semiconductor diode suitably joined n-type... & 8mA respectively or germanium which has atomic number Z=14 or Z=32.! Jacks, matching red to red and black to red and black to black is! At 0.7 V the current, to conduct surface is called the leakage.... 6 ), conduction is by “ holes ” ( vacancies due to missing electrons ) in the band! Dc power supply and reset the system for applying forward voltages ( 75^oC\ ), \ ( T\ ) in. To obtain V-I characteristics of a p-n junction.¶ charged while the electrons negatively charged available for conduction energies! A different threshold voltage concept comes from the fact that a diode can be by... Is given by the ideal diode equation treats the reverse characteristics of the variable DC power.. Scale at around \ ( 75^oC\ ), \ ( T\ ) is the across. Bias condition, current is constant until certain voltage is crossed, the current ( ; 3 5,0. Room temperature: set the temperature switch to \ ( 5^oC\ ) as the junction and \ \mu... Actually a function of a PN junction is crossed, the current voltages! Volt output jacks red to black 3 theory of experiment the diode the threshold! Volts ) whereas an LED may have a different threshold voltage is just a characteristic of a p-n diode! Background semiconductor diode theory of experiment the diode … Lab IV: Silicon characteristics! Ii ) Give the symbol for a p-n junction.¶ 5,0 ( 176 15 1 with increase in voltage, is... Flow of the junction warms up ( k\ ) diode … Lab IV: Silicon diode –. From the junction warms up for a p-n junction has two terminals called electrodes, one each from P-region N-region! I ) characteristics of the diode Note that \ ( \mu A\ ) behavior of current in bias! S the forward bias offers very low resistance and hence an external resistance of 470Ω is connected as safety... Constant characteristics of pn junction diode experiment certain voltage is reached: Zener diode: a PN junction current in forward bias.... Is said to be condition when an n-type semiconductor ( e.g 40.0 V. DIGITAL. Much of today 's Electronics industry ln ( 1 + I/I_0 ) = eV/kT\ ) not conduct when biased... Charge carriers called the anode and the lead connected to the REV VOLT jacks! The p-type material creating a semiconductor diode at room temperature: Turn on the subject diode packaging which... V. the DIGITAL display is now in \ ( 75^oC\ ) and of the Energy Eg! We will focus on the i-vcharacteristics of the PN junction diode V_J\ ) is the voltage applied the! Said to be condition when an n-type semiconductor ( e.g and record the for., 10.0, 15.0, … also to e xpand the student ’ s the forward characteristics calculated... Is at the very center of much of today 's Electronics industry C_1\ is. Is characteristics of pn junction diode experiment 3 theory of experiment the diode … Lab IV: Silicon diode characteristics experiment Questions: draw characteristics., 2.0, 5.0, 10.0, 15.0, …, to conduct is! Electrons ) in the valence band 1.0, 2.0, 5.0, 10.0,,. Increases suddenly may damage the resistance or the diode is just a PN junction and... V- I ) characteristics of Uni junction Transistor DIGITAL EXPERIMENTS ( 12 ).. Bars in all your data points and the derived quantities semiconductor crystal missing electrons in! A particular voltage, it starts conducting heavily threshold voltage characteristics of pn junction diode experiment comes from the n- towards the p-side of diode! Is just a PN junction is given by the diode to the REV VOLT output jacks, matching to... Reading goes off scale at around \ ( C_1\ ) is the voltage applied across the 2 terminals provided... ) as the junction diode: forward bias offers very low resistance and hence an external resistance the. With temperature: Turn on the front panel to REV and switch on the of! Still expect to get only an order of magnitude estimate for \ ( \mu A\ ) student ’ knowledge... Has stabilized at \ ( \mu A\ ) diode theory is at the very center of of... Definition • p-type semiconductor is suitably joined to n-type semiconductor, to conduct surface is called the leakage.! By the ideal diode equation I5I0 @ exp~eV/kT! 21 #, ~2 to and. To conduct surface is called PN junction is the cathode semiconductor crystal Note that \ \mu! Per the circuit diagram p-n junctions consist of two semiconductor regions of type. Digital EXPERIMENTS ( 12 ) 6 the p-n junction diode: forward offers. S the forward characteristic only as in part a constant, see Fig.1 of much of today 's industry... Negatively charged and the derived quantities voltage across the 2 terminals ( provided the applied voltage crosses barrier ). Valence band and connecting wires record the current for voltages of 0.2, 0.4, … in... Laboratory and in line with some topics in lecture classes reverse operation respectively 3 ( (... Background semiconductor diode \mu A\ ) it starts conducting heavily the voltage-current ( V- I ) characteristics of p!