Lecture3-BondingModelsBandgapsAndDopants

Lecture3-BondingModelsBandgapsAndDopants - Lecture 3...

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ECE 3040 - Dr. Alan Doolittle Georgia Tech Lecture 3 Bonding Model and Dopants Reading: (Cont’d) Pierret 1.1, 1.2, 1.4, 2.1-2.6
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ECE 3040 - Dr. Alan Doolittle Georgia Tech Comparison of the Hydrogen Atom and Silicon Atom Hydrogen Silicon ... 3 , 2 , 1 , arg 2 / 2 / tan , 6 . 13 ) 4 ( 2 2 2 0 4 = = = = = = = n and e ch electron q h t cons planks mass electron m where n eV n q m Energy o o electron Hydrogen π ε h h n=1: Complete Shell 2 “s electrons” n=2: Complete Shell 2 “2s electrons” 6 “2p electrons” n=3: 2 “3s electrons” Only 2 of 6 “3p electrons” 4 empty states 4 Valence Shell Electrons
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ECE 3040 - Dr. Alan Doolittle Georgia Tech Pauli Exclusion Principle Only 2 electrons, of spin+/-1/2, can occupy the same energy state at the same point in space.
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ECE 3040 - Dr. Alan Doolittle Georgia Tech Banding of Discrete states and the Simplified Model T=0K E C or conduction band E V or valence band “Band Gap” where ‘no’ states exist
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ECE 3040 - Dr. Alan Doolittle Georgia Tech 4 electrons available for sharing (covalent bonding) in outer shell of atoms
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech
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ECE 3040 - Dr. Alan Doolittle Georgia Tech Ec Ev No “Holes” valence band means no “hole” conduction is possible No electrons in conduction band means no electron conduction is possible Band Occupation at Low Temperature (0 Kelvin) For (E thermal =kT)=0
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ECE 3040 - Dr. Alan Doolittle Georgia Tech + Ec Ev Electron free to move in conduction band “Hole” free to move in valence band Band Occupation at Higher Temperature (T>0 Kelvin) For (E thermal =kT)>0
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ECE 3040 - Dr. Alan Doolittle Georgia Tech + For (E thermal =kT)>0 Carrier Movement Under Bias Direction of Current Flow Direction of Current Flow Ec Ev Electron free to move in conduction band “Hole” movement in valence band
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ECE 3040 - Dr. Alan Doolittle Georgia Tech + Ec Ev Electron free to move in conduction band “Hole” movement in valence band Carrier Movement Under Bias Direction of Current Flow Direction of Current Flow For (E thermal =kT)>0
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ECE 3040 - Dr. Alan Doolittle Georgia Tech + Ec Ev Carrier Movement Under Bias Electron free to move in conduction band “Hole” movement in valence band Direction of Current Flow Direction of Current Flow For (E thermal =kT)>0
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ECE 3040 - Dr. Alan Doolittle Georgia Tech + Ec Ev Carrier Movement Under Bias Electron free to move in conduction band “Hole” movement in valence band Direction of Current Flow Direction of Current Flow For (E thermal =kT)>0 QuickTime Movie
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ECE 3040 - Dr. Alan Doolittle Georgia Tech E c E v The valance band may have ~4e22 cm -3 valence electrons “participating in the bonding processes holding the crystal together. The valance band might only have ~1e6 to 1e19 cm
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This note was uploaded on 08/23/2011 for the course ECE 3040 taught by Professor Doolittle during the Spring '11 term at University of Florida.

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Lecture3-BondingModelsBandgapsAndDopants - Lecture 3...

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