AC LEC 15-10 - Lecture 15 - Energy Band Theory and...

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Lecture 15 - Energy Band Theory and Intrinsic Semiconductors Energy Bands conductors insulators semiconductors Intrinsic Semiconductors thermal excitation of carriers effect of temperature on conductivity
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Conductivity of conductors and insulators is easily explained by bonding Conductors and Insulators
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Valence Electrons in Metals Charge Cloud of electrons Individual Free electrons No Potential Net electron flux = 0 Applied Potential Net electron flux ≠ 0 Drift Velocity ∞ Field
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An alternate explanation for electrical conductivity is energy band theory Conduction in Metals
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Electrons in Isolated Sodium Atom Na: At. No. 11 Group 1 Period 3 1s 2 2s 2 2p 6 3s 1 NOTE Very Defined Energy Levels
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Electrons in Sodium Crystal ONLY Valence Electrons involved Sharp energy levels called Electron States Electron States broadened to continuous Energy Bands
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Metallic Energy Bands Na Na - 3s 1 Mg - 3s 2 Al - 3s 2 3p 1
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Electrons bound due to covalent or ionic bonds Large Energy Gap: 6 – 7 eV Diamond E g = 5.5 eV Energy Bands of Insulators Diamond
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AC LEC 15-10 - Lecture 15 - Energy Band Theory and...

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