Classified by how freely charges move, described by band gap.
Conductors (metals) have free electrons, insulators have a large band gap (>3 eV), and semiconductors (silicon 1.1 eV) sit between and can be doped. Conductivity of semiconductors rises with temperature and doping.
Silicon becomes a conductor of controlled strength when doped with phosphorus.
Materials differ in how freely charge moves, which decides wiring, insulation and the design of all semiconductor devices.
Classified by how freely charges move, described by band gap.
Materials differ in how freely charge moves, which decides wiring, insulation and the design of all semiconductor devices.
The energy gap between the valence and conduction bands. Insulators have a large gap, semiconductors a moderate one, and metals overlap.
Heat excites more electrons across the band gap, so semiconductors conduct better when hot, unlike metals.
Typical applications include selecting copper for wiring and rubber for insulation on a cable, choosing silicon for a transistor because its band gap allows switching and explaining why a diamond insulator does not conduct electricity.
Study "Batteries and internal resistance" first (topic 14 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Band theory. Dielectrics store charge. Superconductors have zero resistance.
Silicon becomes a conductor of controlled strength when doped with phosphorus.
The next topic is "Capacitors", which builds directly on this one.
It is classed as Beginner in Electrical Engineering (topic 15 of 106). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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