# characteristics of pn junction diode experiment

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