{"id":35174,"date":"2016-12-02T16:41:42","date_gmt":"2016-12-02T11:11:42","guid":{"rendered":"https:\/\/www.cbselabs.com\/?p=35174"},"modified":"2021-09-18T15:26:34","modified_gmt":"2021-09-18T09:56:34","slug":"to-draw-the-i-v-characteristic-curve-of-a-p-n-junction-in-forward-bias-and-reverse-bias","status":"publish","type":"post","link":"https:\/\/www.cbselabs.com\/to-draw-the-i-v-characteristic-curve-of-a-p-n-junction-in-forward-bias-and-reverse-bias\/","title":{"rendered":"To draw the I-V characteristic curve of a p-n junction in forward bias and reverse bias"},"content":{"rendered":"
Physics Lab Manual<\/a>NCERT Solutions <\/a>Class 12 Physics Sample Papers<\/a><\/p>\n Aim<\/strong><\/span> Theory<\/strong><\/span> Diagram<\/strong><\/span> Procedure<\/strong><\/span> Observations<\/strong><\/span> 1. \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Table for forward-bias voltage and forward current<\/strong> Calculations<\/strong><\/span> Result<\/strong><\/span> Precautions<\/strong><\/span><\/p>\n Sources of error<\/strong><\/span> Question. 1. Define energy level in an atom.<\/strong> Question. 2. Define energy band in a crystal.<\/strong> Question. 3. Name different types of energy bands.<\/strong> Question. 4. Define different energy bands.<\/strong> Question.5. Name different types of substances.<\/strong> Question. 6. Distinguish between a conductor, an insulator and a semiconductor.<\/strong> Question.7. How are electrical conductivity and resistivity related?<\/strong> Question. 8. What is S.I. unit of conductance?<\/strong> Question. 9. What is order of conductivity of conductors, semiconductors and insulators?<\/strong> Question. 10. Define a hole.<\/strong> Question.11. Define an intrinsic semiconductor.<\/strong> Question. 12. Which materials are commonly used as semiconductors?<\/strong> Question. 13. Which of the upper two materials has less energy gap?<\/strong> Question.14. Define an extrinsic semiconductor.<\/strong> Question.15. Describe an n-type semiconductor (Ge).<\/strong> Question.16. Name the pentavalent impurities which make Ge n-type.<\/strong> Question.17. Describe a p-type semiconductor (Ge).<\/strong> Question.18. Name the trivalent impurities which make Ge p-type.<\/strong> Question.19. What is doping?<\/strong> Question.20. What is order of doping in an extrinsic semiconductor?<\/strong> Question.21. Why is n-type semiconductor so called?<\/strong> Question.22. Why is p-type semiconductor so called?<\/strong> Question. 23. What is a junction?<\/strong> Question.24. What is a depletion layer?<\/strong> Question.25. What is junction potential barrier?<\/strong> Question.26. Why is junction potential barrier so called?<\/strong> Question.27. What is biasing of a junction?<\/strong> Question.28. Give names of the two types of the biasing.<\/strong> Question.29. Why is forward bias so called?<\/strong> Question.30. Why is reverse bias so called?<\/strong> Question.31. How does the bias effect the thickness of the depletion layer?<\/strong> Question.32. How does the bias effect the junction resistance?<\/strong> Question.33. Define characteristic of a junction diode.<\/strong> Question.34. Describe different types of characteristics of a junction diode.<\/strong> To draw the I-V characteristic curve of a p-n junction in forward bias and reverse bias Physics Lab ManualNCERT Solutions Class 12 Physics Sample Papers Aim To draw the I-V characteristic curve of a p-n junction in forward bias and reverse bias. Apparatus A p-n junction (semi-conductor) diode, a 3 volt battery, a 50 volt …<\/p>\n","protected":false},"author":27,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[2],"tags":[],"yoast_head":"\n
\nTo draw the I-V characteristic curve of a p-n junction in forward bias and reverse
\nbias.
\nApparatus<\/strong><\/span>
\nA 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 \u03bcA ammeter, one way key, connecting wires and pieces of sand paper.<\/p>\n
\nForward bias characteristics. 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. With increase in bias voltage, the forward current increases slowly in the beginning and then rapidly. At about 0.7 V for Si diode (0.2 V for Ge), the current increases suddenly. The value of forward bias voltage, at which the forward current increases rapidly, is called cut in voltage or threshold voltage.
\nReverse bias characteristics. 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.
\nWhen reverse bias voltage increases, initially there is a very small reverse current flow, which remains almost constant with bias. But when reverse bias voltage increases to sufficiently high value, the reverse current suddenly increases to a large value. This voltage at which breakdown of junction diode occurs (suddenly large current flow) is called zener breakdown voltage or inverse voltage. The breakdown voltage may^tarts from one volt to several hundred volts, depending upon dopant density and the depletion layer.<\/p>\n
\n
\n<\/p>\n
\nFor forward-bias<\/strong><\/p>\n\n
\n0. 1 V. Current remains zero.<\/li>\n
\nFor reverse-bias<\/li>\n
\nFor forward-bias<\/strong>
\nRange of voltmeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= …..V
\nLeast count of voltmeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= …..V
\nZero error of voltmeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= …..V
\nRange of milli-ammeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= …..mA
\nLeast count of milli-ammeter \u00a0 \u00a0= …..mA
\nZero error of milli-ammeter \u00a0 \u00a0 \u00a0= …..mA<\/p>\n
\n
\nNote.<\/strong> The readings are as a sample.
\nFor reverse-bias
\nRange of voltmeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 = …..V
\nLeast count of voltmeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 = …..V
\nZero error of voltmeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= …..V
\nRange of micro-ammeter \u00a0 \u00a0 \u00a0 \u00a0 \u00a0= …..\u03bcA
\nLeast count of micro-ammeter = …..\u03bcA
\nZero error of micro-ammeter \u00a0 \u00a0= …..
\n2. \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0Table for reverse-bias voltage and reverse current<\/strong>
\n
\nNote.<\/strong> The readings are given as a sample.<\/p>\n
\nFor forward-bias<\/strong>
\nPlot a graph between forward-bias voltage VF<\/sub> (column 2) and forward current IF<\/sub> (column 3) taking VF<\/sub> along X-axis and IF<\/sub> along Y-axis.
\nThis graph is called forward-bias characteristic curve a junction diode.
\n
\n
\nFor reverse-bias<\/strong>
\nPlot a graph between reverse-bias voltage VR<\/sub> (column 2) and reverse current IR<\/sub> (column 3) taking VR<\/sub> along X-axis and IR<\/sub> along Y-axis.
\nThis graph is called reverse-bias characteristic curve of a junction diode.
\n
\n<\/p>\n
\nJunction resistance for forward-bias = 40 ohms
\nJunction resistance for reverse-bias = 2 x 106<\/sup> ohms.<\/p>\n\n
\nThe junction diode supplied may be faulty.<\/p>\nViva Voce<\/strong><\/span><\/h3>\n
\n Answer.<\/strong> Definite energy value of an electron in the subshell of the atom, is called energy level of the atom.<\/p>\n
\n Answer.<\/strong> Broadened energy level (line) in a crystal, is called energy band of the crystal.<\/p>\n
\n Answer.<\/strong> Different energy bands are :
\n1. Conduction band (C), 2. Valence band (V), 3. Forbidden band (F).<\/p>\n
\n Answer.<\/strong> Read Art. 10.03 (1, 2, 3, 4).<\/p>\n
\n Answer.<\/strong> Different types of substances are :
\n1. Conductors, 2. Insulators, 3. Semiconductors.<\/p>\n
\n Answer.<\/strong> Read Art. 10.04 (1, 2, 3).<\/p>\n
\n Answer.<\/strong> Electrical conductivity is reciprocal of resistivity
\n<\/p>\n
\n Answer.<\/strong> S.I. unit of conductance is siemen (S).<\/p>\n
\n Answer.<\/strong>102<\/sup>-108<\/sup>, 105<\/sup>-10-6<\/sup> and 10-11<\/sup>-10-19<\/sup> S m-1<\/sup> respectively.<\/p>\n
\n Answer.<\/strong> A place vacated by an electron, is called a hole. It is associated with a positive charge.<\/p>\n
\n Answer.<\/strong> A pure semiconductor material, is called an intrinsic semiconductor, it\u00a0ne<\/sub> = nn<\/sub><\/p>\n
\n Answer.<\/strong> Silicon and germanium are commonly used as semiconductors.<\/p>\n
\n Answer.<\/strong> Energy gap has value 0.72 eV for germanium and 1.12 eV for silicon.<\/p>\n
\n Answer.<\/strong> A semiconductor material made deliberately impure, is called an extrinsic semiconductor.<\/p>\n
\n Answer.<\/strong> An n-type Ge is obtained by adding a small quantity (one millionth part) of a pentavalent impurity to its crystal.<\/p>\n
\n Answer.<\/strong> The pentavalent impurities are :
\n1. Phosphorus (15), 2. Arsenic (33), 3. Antimony (51), 4. Bismuth (83).
\nGenerally, Arsenic (As) is taken for this purpose.<\/p>\n
\n Answer.<\/strong> A p-type Ge’ is obtained by adding a small quantity (one millionth part) of a trivalent impurity to its crystal.<\/p>\n
\n Answer.<\/strong> The trivalent impurities are :
\n1. Boron (5), 2. Aluminium (13), 3. Gallium (31), 4. Indium (49), 5. Thalium (81).
\nGenerally Indium (In) is taken for this purpose.<\/p>\n
\n Answer.<\/strong> The process of adding a suitable impurity to pure semiconductor, deliberately, is called
\ndoping.<\/p>\n
\n Answer.<\/strong> It is one part in one million.<\/p>\n
\n Answer.<\/strong> Because it contains free electrons with negative charge, as charge carriers.<\/p>\n
\n Answer.<\/strong> Because it contains holes with positive charge, as charge carriers.<\/p>\n
\n Answer.<\/strong> It is a common surface of n-type and p-type semiconductor.<\/p>\n
\n Answer.<\/strong> It is a layer with junction in the middle, having no free charge carriers. The opposite j charge carriers have become neutralized. (It is shown shaded in Fig. 10.02).<\/p>\n
\n Answer.<\/strong> The potential difference between junction ends of the two types of semiconductors, is
\ncalled junction potential barrier.<\/p>\n
\n Answer.<\/strong> Because it prevents free charge carriers from entering the depletion layer by themselves.<\/p>\n
\n Answer.<\/strong> Applying an external potential difference more than potential barrier on the faces of the junction, is called biasing of the junction.<\/p>\n
\n Answer.<\/strong> The two types of biasing are :
\n(i) forward biasing (ii) reverse biasing.<\/p>\n
\n Answer.<\/strong> Because it makes free charge carriers to move forward towards junction.<\/p>\n
\n Answer.<\/strong> Because it makes free charge carriers to move reverse away from junction.<\/p>\n
\n Answer.<\/strong> Forward bias decreases the thickness of depletion layer.
\nReverse bias increases the thickness of depletion layer.<\/p>\n
\n Answer.<\/strong> The forward bias makes junction resistance less.
\nThe reverse bias makes junction resistance more.<\/p>\n
\n Answer.<\/strong> Graph drawn between bias voltage and circuit current of a junction diode, is called characteristic of the diode. It reveals the character (way of behaviour) of the junction diode.<\/p>\n
\n Answer.<\/strong><\/p>\n\n
\nvoltage and circuit current. Junction resistance comes to be about 10 ohm.<\/li>\n