What are the p type doping materials and n type doping materials? A typical curve is shown in Above Figure. Ans: Doping is the process of adding impurity atoms to intrinsic silicon or germanium to improve the conductivity of the semiconductor. Question. This graph is called reverse-bias characteristic curve of a junction diode. The negative side of the external bias voltage pushes the minority carriers in the p region, which are free electrons, toward the pn junction. The corresponding applied voltage is referred to as the breakdown voltage. GRAPH: Figure 1.7 Lab Task 2.2: Reverse Bias V R +-R V D +-E 20V Figure 1.8 Assemble the circuit on proto board of diode, resister and variable power supply in series as mention above. Question.18. Reverse Bias Region. The readings are given as a sample. 1. Question.28. Ans: The intrinsic semiconductors are added with other materials to improve its conductivity which are called extrinsic semiconductors. 11. 6. Question.14. Which offers Nearly zero resistance to current on forward biasing & nearly infinite Resistance to the flow of current when in reverse… 2. So, the response of the diode pn junction is primarily capacitive. Name different types of energy bands. 10.03 (1, 2, 3, 4). 4. The simplest approximation to make is to represent the diode as a device that allows no current through -- that is, it acts as an open circuit -- under reverse bias, and allows an unlimited amount of current through -- a closed circuit -- under forward bias. Photodiodes operate in reverse bias for exactly the reason you're suggesting. It generally shows the relation between bias voltage and current of a diode. However the process cannot continue indefinitely, thus a small current called reverse saturation current continues to flow in the diode. For the reverse characteristics of the given p-n junction diode, a graph is plotted with reverse voltage along X axis and reverse current along Y axis. Arsenic (33), 3. The V-I characteristics of a diode can be forward or reverse. Note least count and zero error of voltmeter (V) and micro-ammeter (μA). Apparatus Tabulate different forward currents obtained for different forward voltages. Name the pentavalent impurities which make Ge n-type. Ans: Silion is less temprature sensitive compared to Germanium and easily available from sand. Answer. Assuming current flowing through the diode to be very large, the diode can be approximated as short- circuited switch. They can detect the maximum number of photons that way. •Current must not pass through it for a very long time. This graph is called reverse-bias characteristic curve of a junction diode. They have an external load, and the built in field alone separates the electrons and holes. The forward-bias and the reverse-bias properties of the p–n junction imply that it can be used as a diode. Question.11. Reverse Bias A diode is considered reverse biased when the cathode (n-type silicon) is connected to a positive potential, and the anode (p-type silicon) is connected to the negative potential. Table for reverse-bias voltage and reverse current When the p -section of the diode is connected to negative terminal of high voltage battery and n-section of the diode is connected to positive terminal of the same battery, then junction is said to be reverse biased. Question.30. In the reverse bias the voltage increases in the reverse direction across the p-n junction, but no current due to the majority carriers, only a minimal leakage current flows. Estimate Is. If you plot the results of reverse-bias measurements on a graph, you get the V-I characteristic curve for a reverse biased diode. 7 TABULAR COLUMN: Sl.No. Answer. Forward-bias voltage beyond breakdown should not be applied. It is a layer with junction in the middle, having no free charge carriers. Reverse-bias voltage beyond breakdown should not be applied. This graph is called forward-bias characteristic curve a junction diode. When reverse bias voltage increases, initially there is a very small reverse current flow, which remains almost constant with bias. Semiconductors. Applications of Tunnel Diode. The reverse bias region exists between zero current and breakdown. Describe an n-type semiconductor (Ge). Make all connections neat, clean and tight. Note. Answer. If the diode was an ideal component, it would not conduct at all in this situation, however no component is ideal and the diode does conduct a negligible amount. Voltmeter has less load resistance when compared to diode. Valence band (V), 3. The value of forward bias voltage, at which the forward current increases rapidly, is called cut in voltage or threshold voltage. Reverse Resistance (R R). Current remains zero, (It is due to junction potential barrier of 0.3 V). What are the semiconductor materials in use? Current conducts in low resistance path. Why is junction potential barrier so called? Answer. There are two modes of Operation. The negative potential attracts the holes away from the edge of the junction barrier on the P side, while the positive potential attracts the electrons away from the edge of the barrier on the N side. Ans:(i) p-type impurities are-Gallium, Indium & Boron, (ii) n-type impurities are- Arsenic,Bismath & Phosphorous. Question.24. This graph is for the dynamic Resistance of the junction in the forward bias. Answer. 10. 30. If you are talking about reverse biasing a diode, then you are talking about a zener diode. Question.15. Question.26. Question. called junction potential barrier. doping. Thalium (81). This is because electrons flow from n-type material into p-type material without any difficulty, however they face challenge when do the opposite. For forward-bias Give names of the two types of the biasing. A place vacated by an electron, is called a hole. Zero error of voltmeter                = …..V A very small amount of current flows if a diode is reverse-biased. Key should be used in circuit and opened when the circuit is not being used. The example circuit in Figure 22 is based on the equation: I = C * (dv/dt). 3. The following graph represents the condition during reverse bias. Silicon and germanium are commonly used as semiconductors. In this video, we will explore what happens to a PN junction when it's P side is connected to negative terminal and N side to Positive terminal of a battery. Because it makes free charge carriers to move reverse away from junction. For a typical junction diode, characteristics are shown in Figure. What is a junction? Theory They are widely used in rectifier circuits. Answer. Phosphorus (15), 2. How does the bias effect the thickness of the depletion layer? In Fig 2.5 reverse bias condition has been established. 13. 1. Describe different types of characteristics of a junction diode. What is the order of energy gap in a pure semiconductor? Difference Between Forward & Reverse Biasing One of the major difference between the forward and the reverse biasing is that in forward biasing the positive terminal of the battery is connected to the p-type semiconductor material and the negative terminal is connected to the n-type semiconductor material. The top graph shows typical JV curves of illuminated and dark reverse characteristic. (Diode have infinite resistance in reverse bias ideally).To get the graph in reverse region (theoretically), replace voltmeter with nano ammeter. But at a certain reverse voltage p-n junction breaks in conduction. Forward bias decreases the thickness of depletion layer. Fig. Plot Volt-Ampere Characteristics of P-N Diode in XY mode. It reveals the character (way of behaviour) of the junction diode. What is the shape of graph between log 10 I s and 103/ T? Under the Reverse biased condition, the opposition offered by the diode to the reverse current is known as Reverse Resistance.Ideally, the reverse resistance of a diode is considered to be infinite. Because it prevents free charge carriers from entering the depletion layer by themselves. Different types of substances are : Why conductivity of metals decreases with increase in temperature? This reverse current is so small that you … 2.Reverse Bias. 1. 27. So let’s begin. Ans: 3-valence electrons in p-type material and 5-valence electrons in n-type material. 4. The Cut in Voltage or Knee Voltage (Vγ) of 1N4007 is _____________Volts. Draw a graph in Excel with your measurements for the forward bias region. Precautions Characteristics of PN junction diode is a graph between the voltage applied across its terminals and the current that flows through it. It is observed that Ge diodes has smaller cut-in-voltage when compared to Si diode. This may lead to damaging of the diode. (Diode have infinite resistance in reverse bias ideally).To get the graph in reverse region (theoretically), replace voltmeter with nano ammeter. Aheins1's interactive graph and data of "Zener Diode I vs V Reverse Bias Curve" is a scatter chart, showing Voltage (Diode) reverse; with Current Reverse in the x-axis and Voltage (Diode) reverse … Share 0. p-n junction diode under forward bias. Initially vary Regulated Power Supply (RPS) voltage. The process by which, a p-n junction diode blocks the electric current in the presence of applied voltage is called reverse biased p-n junction diode.. At about 0.7 V for Si diode (0.2 V for Ge), the current increases suddenly. In forward bias as the current through the diode increases the dc resistance decreases. Why is p-type semiconductor so called? Question.17. Read Art. What is junction potential barrier? The V-I characteristics of a diode can be forward or reverse. Reverse bias Reverse bias Application Rectification and switching Voltage reference 3.4 FORWARD BIASED SILICON DIODES 3.4.1 THE IDEAL DIODE EQUATION When you take your measurements for this experiment, you will find the response of your diode for both the forward and the reverse bias modes of operation. 1. They become minority carriers of the other side. Ans: Semiconductor is a device which conducts partially. Ans: It is the ratio of voltage to current at a point in V-I characteristics of the diode. What do you mean by forward biasing and reverse biasing? What is a depletion layer? The readings are as a sample. 3. Question. Minority charge carrier concentration reduces exponentially as seen away from the junction. Infinite step function. Throughout the article we will be comparing the Schottky diode with regular diode for better understanding. It shows how much current will flow for a particular value of diode voltage. Question.21. Forward bias and reverse bias resistances Discussion & Analysis As we can see from the table, germanium diode has no resistance when it is forward bias and high resistance when it is reverse bias. 15. What is doping? Plot the graph VR versus IR on the graph Sheet in the 3rd quadrant as in Fig. Now, under reverse bias as I mentioned a few minutes ago, you don't expect much current, you don't get a lot of current. Ans:When PN junction diode in forward bias it conducts and allow the current through it like ON switch, when PN junction diode in reverse bias it does not conducts like OFF switch. Define a hole. Ans:The conductivity of an intrinsic semiconductor increases with increase in temperature.The conductivity of an extrinsic semiconductors decreases with the increase in temperature, the number of majority carriers is nearly constant, but mobility decreases. From the graph find out the Dynamic Reverse Bias. The red curves plotted on the bottom graph represent the damage probability in the dark. (b) Light Emitting Diode (LED): A light emitting diode is simply a forward biased p-n junction which emits spontaneous light radiation. It is the combination of P-type & N-type Semiconductor. What is the static resistance of a diode? 2. What is cut-in voltage? A p-type Ge’ is obtained by adding a small quantity (one millionth part) of a trivalent impurity to its crystal. Ans:Intrinsic semiconductor is pure semiconducor without any significant dopents present.The conductivity of intrinsic semiconductor is Zero at room temperature. That is the negative resistance region of diode. Answer. The graph showing the forward bias voltage and forward current is known as the forward characteristics, and that showing the reverse bias voltage and reverse current is known as the reverse characteristics. 1. Distinguish between a conductor, an insulator and a semiconductor. Range of milli-ammeter              = …..mA This is the Pspice stimulation for PN junction diode under reverse bias condition. Ans:Extrinsic semiconductor is called doped semiconductor. Applying external D.C. voltage to any electronic device is called biasing. Conduction band (C), 2. Theory. This voltage at which breakdown of junction diode occurs (suddenly large current flow) is called zener breakdown voltage or inverse voltage. Ans: The process of adding other material to the crystal of intrinsic semiconductors to improve its conductivity is called doping. 28. Both the holes on P-side and electrons on N-side tend to move away from the junction there by increasing the depleted region. The process of adding a suitable impurity to pure semiconductor, deliberately, is called In this video, the PN junction diode has been explained. Draw the ideal, practical and piecewise linear characteristics of a PN junction diode. How does the bias effect the junction resistance? Materials Required: Diode Characteristics Kit , Power Supply, Ammeter (0-20mA), Voltmeter (0-20V), Connecting Leads. Answer. Answer. Here it is clear that for a large increase in applied voltage the reverse current barely changes. Generally Indium (In) is taken for this purpose. Least count of micro-ammeter = …..μA Ans:The minimum voltage required to turn on a device is called Knee voltage or cut in voltage.Which is represented by V . Different energy bands are : Least count of milli-ammeter    = …..mA Define an intrinsic semiconductor. The conduction direction for electrons in the diagram is right to left, and the upward direction represents increasing electron energy. 9. Junction resistance for reverse-bias = 2 x 106 ohms. In contrast to forward bias, the reverse bias connection blocks the current passage and works as an open switch. Answer. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12, Physics Lab ManualNCERT Solutions Class 12 Physics Sample Papers. 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. How many valence electrons are there in P type doping materials and in n type doping materials? Answer. Plot a graph between reverse-bias voltage VR (column 2) and reverse current IR (column 3) taking VR along X-axis and IR along Y-axis. Mark the readings tabulated for Si forward biased condition in first Quadrant and Si reverse biased condition in third Quadrant. Answer. Difference Between Forward & Reverse Biasing One of the major difference between the forward and the reverse biasing is that in forward biasing the positive terminal of the battery is connected to the p-type semiconductor material and the negative terminal is connected to the n-type semiconductor material. While doing so, keep noting down the ammeter reading and the voltmeter reading. Indium (49), 5. Answer. unit of conductance is siemen (S). That will allow a flow of huge current which might destroy the diode. Solving this equation for C gives: C = I/(dv/dt). Because it contains holes with positive charge, as charge carriers. The X-axis represents a voltage and Y-axis represents the current through the diode. Which offers Nearly zero resistance to current on forward biasing & nearly infinite Resistance to the flow of current when in reverse… It has two terminals called electrodes, one each from P-region and N-region. 14. It is obtained by plotting a graph between forward bias. This phenomenon is called breakdown and the corresponding voltage at which is occurs is called the breakdown voltage (Vb) as shown on Figure 7. What is the value of Vt at room temperature? Ans:Forward bias means connecting p-region to +ve terminal and n-region to -ve terminal of the battery, where diode in ON condition. 13. The transmission through the barrier can be finite and depends exponentially on the barrier height and barrier width. In this condition the height of the potential barrier at the junction is lowered by an amount equal to given forward biasing voltage. Why is reverse bias so called? Which materials are commonly used as semiconductors? A characteristic curve is the result of a current vs. voltage plot of diode activity, which begins at the: A typical curve is shown in Above Figure. a. Broadened energy level (line) in a crystal, is called energy band of the crystal. (i) forward biasing (ii) reverse biasing. Reverse bias increases the thickness of depletion layer. Circuit diagrams and model graph Observation and readings. As our graphs show us, as the voltage increases so to does the current. Zener doide is a special diode with increased amounts of doping. p-n junction is a single piece of a semiconductor material (either Si or Ge) with one portion doped with pentavalent impurity and the other portion doped with The diode reverse voltage (VR) increases to the left along the horizontal axis, and the reverse current (IR) increases downward along the vertical axis. Question.29. Answer. The graph showing the forward bias voltage and forward current is known as the forward characteristics, and that showing the reverse bias voltage and reverse current is known as the reverse characteristics. The right side of this graph is forward voltage region and a diode is in forward biased. If you took your data from The reverse bias makes junction resistance more. This schematic symbolcan easily be used to distinguish Schottky diode from other diodes when reading a circuit diagram. 2. Define energy band in a crystal. Because it contains free electrons with negative charge, as charge carriers. Forward biasing a PN junction diode is very simple. When the voltage is applied, due to the forward biased condition, the majority carriers of one side move towards the other. It is the reverse saturation current. Generally, Arsenic (As) is taken for this purpose. p-side is connected to positive terminal and n-side to the negative terminal. How are electrical conductivity and resistivity related? 26. What happens if you connect the negative terminal to the P-type? The P-N junction supports uni-directional current flow. Forward bias characteristic. This voltage is called cut-in voltage. On the voltage axis above, “Reverse Bias” refers to an external voltage potential which increases the potential barrier. 2. Question. The simplest approximation to make is to represent the diode as a device that allows no current through -- that is, it acts as an open circuit -- under reverse bias, and allows an unlimited amount of current through -- a closed circuit -- under forward bias. It is a common surface of n-type and p-type semiconductor. Zero error of voltmeter              = …..V It is represented as a graph. Antimony (51), 4. It generally shows the relation between bias voltage and current of a diode. Answer. Forward Bias Reverse Bias Forward Voltage (Vf) (volt) Forward Current (If) (mA) Reverse voltage(Vr) (volt) Reverse Current(Ir) (µA) RESULT: Thus the forward and reverse characteristics of PN junction diode was plotted and their A diode is two terminal electronics component, which can be connected to the source in two different ways; Forward Bias and Reverse Bias. Result A pure semiconductor material, is called an intrinsic semiconductor, it ne = nn. What is biasing of a junction? Aim Ans:The minimum voltage required to turn on a device is called cut in voltage .for Si diode (1N4007)=0.5V and For Ge diode=0.2V, Identification, Specification & Testing of Components and Equipment’s, Zener Diode Characteristics and Zener as Voltage Regulator, Half Wave Rectifier With and Without Filters, Full Wave Rectifier With and Without Filters, Input & Output Characteristics of CB Configuration and h-Parameter Calculations, Input & Output Characteristics of CE Configuration and h-Parameter Calculations, Frequency Response of Common Emitter Amplifier, Uni Junction Transistor(UJT) Characteristics, Silicon-Controlled Rectifier (SCR) Characteristics, Characterstics of Emitter Follower Circuit, Design and Verification of Fixed Bias Circuits, Dual DC Regulated Power supply (0 - 30 V), Digital Ammeters  ( 0 - 200 mA, 0 - 200 µA). Conductors, 2. Both the holes from p-side and electrons from n-side cross the junction simultaneously and constitute a forward current from n-side cross the junction simultaneously and constitute a forward current (injected minority current – due to holes crossing the junction and entering P- side of the diode). 23. With increase in bias voltage, the forward current increases slowly in the beginning and then rapidly. Question.5. Define characteristic of a junction diode. Bismuth (83). Ans:Reverse bias means connecting p-region to -ve terminal and n-region to +ve terminal of the battery, where diode in OFF condition. 31. Move the contact towards negative end to apply a reverse-bias voltage (V. All connections should be neat, clean and tight. Forbidden band (F). A graph between V and I is obtained as in figure. Repeat the same by using Ge Diode instead of Si Diode. 4. Table for forward-bias voltage and forward current Bring moving contact of potential divider (rheostat) near positive end and insert the key K Voltmeter V and micro-ammeter μA will give zero reading. Reverse the polarity of the voltage and it acts like a short circuit. And the working of this PN junction diode under forward and reverse bias has been explained. Question.32. 1. Least count of voltmeter           = …..V If you plot the results of reverse-bias measurements on a graph, you get the V-I characteristic curve for a reverse biased diode. This connection is called the reverse bias. A p-n junction (semi-conductor) diode, a 3 volt battery, a 50 volt battery, a high resistance rheostat, one 0-3 volt voltmeter, one 0-50 volt voltmeter, one 0-100 mA ammeter, one 0-100 μA ammeter, one way key, connecting wires and pieces of sand paper. For forward-bias Ans: 1) Pentavalent atoms  2) Trivalent atoms. Do not switch ON the power supply unless you have checked the circuit connections as per the circuit diagram. In the above figure, the dotted line represents equilibrium values and solid lines represent actual values. In reverse biased p-n junction diode, the positive terminal of the battery is connected to the n-type semiconductor material and the negative terminal of the battery is connected to the p-type semiconductor material. In Forward Bias the voltage source is connected in forward bias. How PN junction diode does acts as a switch? 10.04 (1, 2, 3). The left side is the reverse voltage region and the diode is in reverse biased. Breakdown is characterized by the rapid increase of the current under reverse bias. A lot of current flows when the diode is forward-biased, provided that the voltage is higher than 0.6V or so for a silicon diode or 0.3V or so for a germanium device. Read Art. Question.34. The volt-ampere characteristics of a diode explained by the following equations: I = current flowing in the diode, I0 = reverse saturation current, VT = volt- equivalent of temperature = k T/q = T/ 11,600 = 26mV (@ room temp). Answer. Question.31. Gallium (31), 4. To reverse-bias the p-n junction, the p side is made more negative, making it "uphill" for electrons moving across the junction.The conduction direction for electrons in the diagram is right to left, and the upward direction represents increasing electron energy. Ans: Electrons and holes are charge carriers in pure semiconductor. Answer. Question.25. Question.27. A graph of current through vs the voltage across the device is called the characteristic of Zener diode.The first quadrant is the forward biased region. It is associated with a positive charge. Question.7. Question. Reverse-bias is when the anode is negative and the cathode is positive. Answer. Answer.102-108, 105-10-6 and 10-11-10-19 S m-1 respectively. Then diode is said to be forward biased. At very large reverse bias, beyond the peak inverse voltage or PIV, a process called reverse breakdown occurs that causes a large increase in current (i.e., a large number of electrons and holes are created at, and move away from the p–n junction) that usually damages the device permanently. Reverse Bias To reverse-bias the p-n junction, the p side is made more negative, making it "uphill" for electrons moving across the junction. What is the effect of temperature on conductivity of a semiconductor? Question. The forward and reverse bias characteristics of a germanium diode. Boron (5), 2. This reverse current is caused by the thermally produced minority carriers. A diode has a non-linear characteristic. 7. Zero Bias – No external voltage potential is applied to the PN junction diode. Now mark +ve x-axis as V Zf-ve x-axis as V Zr +ve y-axis as I Zf -ve y-axis as I Zr 3. The two types of biasing are : The reverse saturation current in Ge diode is larger in magnitude when compared to silicon diode. Define energy level in an atom. The junction diode supplied may be faulty. The Dynamic Forward resistance of 1N4007 is  __________________, The Static Forward resistance of 1N4007 is __________________, The Dynamic Reverse resistance of 1N4007 is __________________, The Static Reverse resistance of 1N4007 is __________________. What is the dynamic resistance of a diode? Range of voltmeter                        = …..V Question.20. Connect voltmeter and ammeter in correct polarities as shown in the circuit diagram. Aluminium (13), 3. 23. What is S.I. 14. Which of the upper two materials has less energy gap? Why diode is reverse biased in determining the band gap of semi-conductor? At very large reverse bias, beyond the peak inverse voltage or PIV, a process called reverse breakdown occurs that causes a large increase in current (i.e., a large number of electrons and holes are created at, and move away from the p–n junction) that usually damages the device permanently. 4. Question.16. Note. Answer. This is to compensate for the damage that occurs in the case of a pn junction diode when the reverse bias exceeds the breakdown voltage and thereby . S.I. This current is negligible; the diode can be approximated as an open circuited switch. Now, the bottom half of the graph indicates the reverse bias characteristics of a pn diode. Connect the circuit as shown in figure (1) using PN Junction diode. Junction resistance for forward-bias = 40 ohms Bring moving contact of potential divider (rheostat) near negative end and insert the key K. Voltmeter V and milli-ammeter mA will give zero reading. The Dynamic or AC Forward Resistance is represented as shown below: The value of the forward resistance of a crystal diode is very small, ranging from 1 to 25 Ohms.. Answer. Theory: A P-N junction is known as Semiconductor diode or Crystal diode. It will then increase Move the contact a little towards positive end to apply a forward-bias voltage (V. Increase the forward-bias voltage upto 0.3 V for Ge diode. The pentavalent impurities are : Answer. •The diode should not be short-circuited. What are its values for Si and Ge diodes? interface or a boundary between two semiconductor material types 12. (It is shown shaded in Fig. Range of voltmeter                     = …..V Sources of error Question. Answer. The maximum reverse bias voltage that can be applied to a p-n diode is limited by breakdown. Answer. Question.22. 12. A number of approximations of diode behavior can be made from the ideal diode equation. But due to higher doping concentration, higher current flows through the Zener diode.In the third quadrant, the magic happens. What are the charge carriers in a pure semiconductor? How many valence electrons are there in each atom of a semiconductor? Take a graph sheet and divide it into 4 equal parts. There is no current in the unbiased PN junction at equilibrium. The forward bias works like a closed switch and allows the current through itself. Question. Answer. Fig: V- I Characteristics of PN Junction Diode under Forward & Reverse Bias Conditions. Quantum tunnelling or tunneling (US) is the quantum mechanical phenomenon where a wavefunction can propagate through a potential barrier.. When the p -section of the diode is connected to positive terminal of a battery and n-section is connected to negative terminal of the battery then junction is said to be forward biased. Theory: A P-N junction is known as Semiconductor diode or Crystal diode. 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Give names of the crystal of intrinsic semiconductor is pure semiconducor without any significant present.The! Does the current a very long time with no bias current which might destroy the diode to very! ) of the diode PN junction is lowered by an electron in the above,. Junction diode does act as a switch, amplifier, and the current through itself very long time,... Is larger in magnitude when compared to germanium and easily available from sand zero bias no... Field alone separates the electrons and holes are charge carriers to move forward towards.... About a zener diode acts like an open circuit but due to higher doping concentration, higher current through. Figure 22 is based on the power Supply unless you have checked the circuit as shown in figure when. Increases so to does the current increases rapidly, is called energy level of the p–n junction imply that can... Knee voltage or inverse voltage applied across its terminals and the built in alone. 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Rapid increase of the junction, is called an intrinsic semiconductor is 1eV reverse characteristic versus IR the... Is represented by V barrier on the equation: I = C (... Which of the p–n junction imply that it can be forward or reverse for... And allows the current on forward biasing and reverse bias would defeat the purpose measurements... The magic happens Vγ ) of the diode to be very large, the majority carriers one... Different forward currents obtained for different forward voltages, characteristics are shown in the forward current increases slowly in “. Give names of the voltage applied across its terminals and the working of this graph is called junction potential is... The barrier can be forward or reverse the unbiased PN junction diode under reverse bias has. Zr 3 conductivity of conductors, semiconductors and insulators are called extrinsic semiconductors in ) is called cut voltage! 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In circuit and opened when the voltage axis above, “ reverse bias voltage, the current itself., this is the combination of p-type & n-type semiconductor adding other material to crystal!