# characteristics of pn junction diode experiment

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