Eng 45 - Chapter 1 - Structure(32)

Eng 45 - Chapter 1 - Structure(32) - Fermi energy is...

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Materials Science Fall, 2007 Page 31 tially filled states of the conduction band can conduct electricity, and there is also some conductivity in the valence band because of the vacant states there. In an intrinsic semiconductor the number of conduction electrons (n) is equal to the number of holes (p) and is given approximately by the Arrhenius function n » N 0 e - E G 2kT 2.9 The Fermi energy, E F , is the energy of a state that has probability 1/2 of being filled by an electron. In an intrinsic semiconductor or insulator it is located in the center of the band gap. E E G x E F valence band filled conduction band empty Fig. 2.11: Band configuration in an intrinsic semiconductor or insulator. The valence band is filled, the conduction band empty. The
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Unformatted text preview: Fermi energy is located in the center of the band, dividing the filled and empty states. The magnitude of the band gap, E G , determines whether the material is called a semiconductor or insulator. When the band gap, E G , is large the number of conduction electrons is very small. The conductivity is low and the material is an insulator. As E G decreases the number of conduction electrons increases. The conductivity becomes mea-surable and the material is called a semiconductor. Thank you for evaluating AnyBizSoft PDF Splitter. A watermark is added at the end of each output PDF file. To remove the watermark, you need to purchase the software from http://www.anypdftools.com/buy/buy-pdf-splitter.html...
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This note was uploaded on 01/26/2010 for the course ENGLISH 45 taught by Professor Morris during the Spring '10 term at University of California, Berkeley.

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Eng 45 - Chapter 1 - Structure(32) - Fermi energy is...

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