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‘Semiconductor Physics’

‘Semiconductor Physics’. Energy levels Of Materials. Energy levels. Energy levels. Types Of Semiconductors . -Intrinsic -Extrinsic. Types of Extrinsic-. N-Type. What is Diode?. Improving Conduction by Doping (cont.). Improving Conduction by Doping (cont.).

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‘Semiconductor Physics’

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  1. ‘Semiconductor Physics’

  2. Energy levels Of Materials

  3. Energy levels

  4. Energy levels

  5. Types Of Semiconductors -Intrinsic -Extrinsic

  6. Types of Extrinsic-

  7. N-Type

  8. What is Diode?

  9. Improving Conduction by Doping (cont.)

  10. Improving Conduction by Doping (cont.)

  11. Improving Conduction by Doping (cont.)

  12. P-N Junction – Forward Bias • positive voltage placed on p-type material • holes in p-type move away from positive terminal, electrons in n-type move further from negative terminal • depletion region becomes smaller - resistance of device decreases • voltage increased until critical voltage is reached, depletion region disappears, current can flow freely

  13. Reverse Bias

  14. --Rectifiers---

  15. Half-wave Rectifiers • Half-wave rectifier – A diode placed in series between a transformer (or ac line input) and its load.

  16. Positive Half-wave Rectifiers This circuit converts an ac input to a series of positive pulses.

  17. Full Wave Rectifier

  18. ----Transistors---

  19. Transistor as a Switch Transistor Switch

  20. Introduction to Transistors The terms used for the 3 terminals of a transistor are: “the emitter”, “the collector”, and “the base”

  21. Introduction to Transistors • The common schematic symbols used for transistors • The “emitter” always has a line with the arrow • The “base” is the heavy line at the bottom of the symbol • The “collector” is the line without the arrow

  22. Transistor Operation “Amplification” aspects of a transistor

  23. Why do Frequency limits occur? • It takes a certain time for e- to travel from emitter to collector (transit time) • If frequency is too high, applied current varies too rapidly • Electrons may be unable to dislodge rapidly enough to move from E to C before current surges in the other direction. Making the base thinner reduces transit time and improves frequency response

  24. Energy levels

  25. Working pnp/npn

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