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Doping Silicon To Control It's Conduction Properties.
Member rating: No Rating | Words: | Submitted: Tue Jan 27 2004
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Section C Case Study - Doping Silicon To Control It's Conduction Properties. Material Properties Silicon is one of the class of materials called SEMICONDUCTORS. So-called because their resistivity lies between good conductors (e.g. metals) and good insulators (e.g. many plastic materials). At room temperature some important resistivities are: Material Resistivity/?m silver 1.5x10-8 gold 2.1x10-8 copper 1.6x10-8 silicon 0.6 germanium 0.5 quartz glass 1x1016 acrylic 1x1014 At 0K, (i.e. -273.150C), silicon is a perfect insulator. At this temperature, silicon has no free mobile charge carriers because all electrons (negative charge carriers) and holes (positive charge carriers), are bonded to a silicon atom with their covalent bonds. Silicon is in group IV of the Periodic Table which means that it has 4 electrons in the outermost electron orbital-these are called VALENCE electrons as they are responsible for bonding the silicon structure together. In a 2-dimensional representation, this would look like the following: As the above sketch shows, at 0K all electrons are bonded to Si atoms and are not free to carry...
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