Lecture 03 Winter 2010

Lecture 03 Winter 2010 - 1 ECSE 330 ECSE 330 Introduction...

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Unformatted text preview: 1 ECSE 330 ECSE 330 Introduction to Electronics Lecture 02: Operational Amplifiers Roni Khazaka Silicon Silicon Atomic number 14 Atomic weight: 28 09au electron Atomic weight: 28.09au The material is the most purified substance man has ever attempted to produce. It has 4 valence electrons R. Khazaka ECSE330 Introduction to Electronics 2 and if properly grown in crystal-form it takes on a face-body cubic crystal pattern. neutron proton 2 Silicon Semiconductor. Intrinsic silicon has a regular crystal lattice of atoms held together by covalent bonds each atom has four valence electrons R. Khazaka ECSE330 Introduction to Electronics 3 5 10 22 atoms/cm 3 Rubber Silicon (semi-conductor) Copper Intrinsic Silicon R. Khazaka ECSE330 Introduction to Electronics 4 At low temperatures, all covalent bonds are intact (T 0K), there are no free electrons 3 Intrinsic Silicon Electron Hole pair R. Khazaka ECSE330 Introduction to Electronics 5 As temperature rises, some electrons break free, leaving holes in lattice with positive charge. These are called Electron-hole pairs . The electrons move in the conduction- band and holes move in the valence-band Intrinsic Silicon The number of holes p and the number of electrons n increases equally with temperature. At room-temperature (T>273K), n = p = 1.5 10 10 carriers/cm 3 . p n n i = = np n i = 2 R. Khazaka ECSE330 Introduction to Electronics 6 4 Electron Hole Recombination Electrons in conduction band and holes in valence band may interact with each other. A free electron and a free hole interact and annihilate each other. R. Khazaka ECSE330 Introduction to Electronics 7 Before After Semiconductor Doping Extra electron Phosphorous-doping This atom has 5 valence electrons Extra FREE electron electrons....
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Lecture 03 Winter 2010 - 1 ECSE 330 ECSE 330 Introduction...

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