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Key Concepts

Conduction Mechanism in Metals

Metallic conduction is characterized by a high density of free electrons that are delocalized from their atomic cores and flow freely through the lattice. Unlike semiconductors, metals have a partially filled conduction band, making their conductivity primarily determined by electron mobility rather than impurity levels, which generally exert a much smaller relative effect on their overall conductivity.

Impurity Doping

Impurity doping refers to the deliberate addition of specific atoms (impurities) into a semiconductor to modify its electrical properties. These impurities introduce extra electrons or holes into the semiconductor’s crystal lattice, significantly altering the charge carrier concentration and, hence, the material's conductivity.

Charge Carrier Concentration

The conductivity of a semiconductor is highly dependent on the number of available charge carriers, namely electrons and holes. Impurities change the intrinsic balance by supplying extra carriers through donor or acceptor states, leading to an adjustable conductivity that is crucial for the functionality of semiconductor devices.

Conduction Mechanism in Semiconductors

In semiconductors, electrical conduction occurs as charge carriers are thermally excited across the band gap or are introduced by impurity doping. This means that even slight variations in impurity content can lead to significant changes in conductivity because the number of carriers is relatively low compared to metals.

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