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ANALOG ELECTRONIC (BEL 10203)

ANALOG ELECTRONIC (BEL 10203). By: DR. NAFARIZAL BIN NAYAN Department of Electronic Engineering Faculty of Electrical and Electronic Engineering Universiti Tun Hussein Onn Malaysia. Lecture contents. Revision on previous lecture. I ntrinsic and extrinsic semiconductor

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ANALOG ELECTRONIC (BEL 10203)

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  1. ANALOG ELECTRONIC (BEL 10203) By: DR. NAFARIZAL BIN NAYAN Department of Electronic Engineering Faculty of Electrical and Electronic Engineering Universiti Tun Hussein Onn Malaysia

  2. Lecture contents Revision on previous lecture • Intrinsic and extrinsic semiconductor • Formation of p-n junction • Distribution of holes and electrons • Potential difference of p-n junction • Forward-biased and Reversed-biased p-n junction • IV characteristics of forward-biased and reversed-biased p-n junction

  3. Energy band Example: Orbital shells K L M Energy band in Silicon Atom Revision on previous lecture • The outermost atom- valence shell The orbital shells for an atom

  4. Intrinsic and extrinsic semiconductor • Intrinsic semiconductor chemically very pure and poor in conductivity. It has equal numbers of negative carriers (electrons) and positive carriers (holes). Contain no impurity atoms. What are the example? - Silicon and Germanium The Silicon bonding

  5. Extrinsic semiconductor Semiconductor material intentionally doped with impurity. Doping : The process of adding specific types of atoms to a semiconductor to favorably alter electric characteristics • 2 types of extrinsic (impure) semiconductor; • N-type • P-type

  6. When an impurity increases the number of free electrons, the doped semiconductor is NEGATIVE or N-TYPE semiconductor. • An impurity that reduces the number of free electrons, causing more holes, creates a POSITIVE or P-TYPE semiconductor.

  7. N– type material • Diffused impurities with • 5 valence electrons are • called donor atoms. Antimony (Sb) impurity in n-type material

  8. P-type material • The diffused impurities • with 3 valence electrons • are called acceptor • atoms. Boron (B) impurity in p-type material

  9. Formation of p-n junction Fundamental component of many electronic devices. A PN junction is fabricated from a single slice of semiconductor. One side doped with acceptor impurity atoms – p region One side doped with donor impurity atoms – n region

  10. Diffusion Process • In trying to neutralize charges • free electrons in n-type diffuse across junction to p-type. • free holes in p-type diffuse to n-type. • electrons & holes close to the junction recombine. The movement of holes and electrons in diffusion process.

  11. Depletion region as a result, P N E-field force on holes E-field force on electrons E-field A depletion region formed due to electrons and holes movement in diffusion process and electric field.

  12. Reverse-bias voltage • opposite polarity • depletion region widens • very low current flows Forward-biased and Reversed-biased p-n junction • Forward-bias voltage • charge repel • depletion region narrows • the current flows

  13. IV characteristics of forward&reversed-biased Forward current Resistor: To ? To limit the current and prevent overheat Figure 1.15: Forward-biased voltage

  14. Extremely small reverse current Breakdown voltage (VBR) • IV characteristics of forward&reversed-biased Silicon diode ? Barrier potential

  15. Commercial Break GENG V2

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