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