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Unformatted text preview: 10²³ particles/cm³ Silicon has 4 valence electrons, it covalently bonds with four adjacent atoms in the crystal lattice Higher temperatures create f ree charge carriers. A “ hole” is created in the absence of an electron. At 23C there are 10¹º particles/cm³ of free carriers DOPING DOPING There are two types of doping N-type and P-type. The N in N-type stands for negative. A column V ion is inserted. The extra valence electron is free to move about the lattice The P in P-type stands for positive. A column III ion is inserted. Electrons from the surrounding Silicon move to fill the “ hole.” Energy-band Diagram Energy-band
s s s A very important concept in the study of semiconductors is the very energy-band diagram energy-band It is used to represent the range of energy a valence electron can It have have For semiconductors the electrons can have any one value of a For continuous range of energy levels while they occupy the valence shell of the atom shell
– That band of energy levels is called the valence band That valence s Within the same valence shell, but at a slightly higher energy Within level, is yet another band of continuously variable, allowed energy levels levels
– This is the conduction band This conduction Band Gap Band
s s s s Between the valence and the conductio...
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This note was uploaded on 04/04/2010 for the course EE 3 taught by Professor Staff during the Winter '08 term at UCLA.
- Winter '08