free electron

physics

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June 26, 2026

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A free electron is an electron that is not permanently attached to an atom and can move freely within a substance or vacuum. In conductors like metals, these free electrons form an "electron gas" that allows for the flow of electrical current. Materials with free electrons are good conductors, while those with tightly bound electrons act as insulators. In semiconductors, the number of free electrons can be increased by heat or impurities, significantly altering their conductivity. Unlike bulk matter, the properties of small clusters of atoms can vary greatly with the number of constituent particles, including their binding energies and electronic structures.12345

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semiconductor device
Electronic properties
…of a bond yields a free electron that can participate in current conduction. Once an electron moves away from a covalent bond, there is an electron deficiency in that bond. This deficiency may be filled by one of the neighbouring electrons, which results in a shift of the deficiency location…
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…of a bond yields a free electron that can participate in current conduction. Once an electron moves away from a covalent bond, there is an electron deficiency in that bond. This deficiency may be filled by one of the neighbouring electrons, which results in a shift of the deficiency location…
Read More

solar cell
Solar cell structure and operation
…the junction-forming layers, these “free” electrons are in random motion, and so there can be no oriented direct current. The addition of junction-forming layers, however, induces a built-in electric field that produces the photovoltaic effect. In effect, the electric field gives a collective motion to the electrons that flow…
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…the junction-forming layers, these “free” electrons are in random motion, and so there can be no oriented direct current. The addition of junction-forming layers, however, induces a built-in electric field that produces the photovoltaic effect. In effect, the electric field gives a collective motion to the electrons that flow…
Read More