03++DOS+_+Fermi+Statistics

03++DOS+_+Fermi+Statistics - Review Energy Bands conduction...

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Review: Energy Bands conduction “band edge” E vac Core electrons valence electrons Conduction band E C Energy Bandgap E V valence “band edge” (mostly empty) (mostly filled) Pauli Exclusion Principle + Band diagram
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Review: Effective Mass Band Structure: Energy-Momentum Relations Free electron Semiconductor E p E p E C * 2 2 n m p E 1 2 2 * ) ( = dp E d m n 0 2 2 m p E =
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Review: Electrons and Holes E C E V E Electrons: like ball rolling down hill Holes: like bubble floating to surface Two independent conduction mechanisms What is the number of available electron (hole) states in a semiconductor? How are charge carriers distributed in energy?
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EECS 320 Density Of States
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Football Stadium Analogy
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Electronic states Start with a piece of semiconductor material How would you define the number of electron states?
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Electronic states Electron states distributed in energy Semiconductor Valence band filled with electrons Core electrons valence electrons Conduction band E vac Energy Bandgap Electron states are not uniformly distributed in energy We are primarily concerned with states near E C and E V
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States In Conduction/Valence Band Recall Conduction and Valence Band Define electron states in conduction band E E C No states in the bandgap E V Define “hole” states in valence band Number of states Unit volume x Unit energy Density Of States = (Note we have 4-D, 3-D in space + energy)
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Density Of States Density of states may be determined if bandstructure is known Conduction Band E G p=0 Valence Band p Near bandedge (E C and E V ), approximate using effective mass m n * and m p * E E C E V
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This note was uploaded on 08/09/2011 for the course EE 320 taught by Professor Zhongzhaohui during the Summer '11 term at Shanghai Jiao Tong University.

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03++DOS+_+Fermi+Statistics - Review Energy Bands conduction...

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