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n-p-n transistor
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A diagram showing a cross section of an n-p-n transistor with labeled gate, source, and drain on the left, and its electronic circuit symbol with the same labels on the right. amplifier using an n-p-n transistor (A) Perspective of a p-n-p bipolar transistor; (B) idealized one-dimensional transistor; (C) symbols for p-n-p and n-p-n bipolar transistors (E is an emitter, B is a base, and C is a collector). bipolar transistor
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n-p-n transistor

electronics
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A diagram showing a cross section of an n-p-n transistor with labeled gate, source, and drain on the left, and its electronic circuit symbol with the same labels on the right.
cross section of an n-p-n transistor An n-p-n transistor and its electronic symbol.

An n-p-n transistor is a fundamental semiconductor device where both electrons and holes participate in electrical conduction. It functions by controlling a larger output current with a smaller input voltage applied to its base.1

The transistor is constructed from three layers of semiconductor material: an emitter, a base, and a collector. In an n-p-n transistor, the emitter and collector are n-type (rich in electrons), and the base is p-type (rich in holes). Doping, the process of adding impurities to silicon, creates these n-type and p-type regions.123

When the emitter-base junction is forward-biased and the base-collector junction is reverse-biased, electrons from the emitter are injected into the base. If the base is narrow enough, most of these electrons reach the collector, creating a current flow. This allows the transistor to amplify signals, making it crucial for amplifiers, oscillators, and integrated circuits.1

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4 Britannica Sources
  1. semiconductor device - Bipolar transistors
  2. dopant
  3. integrated circuit - Doping silicon
  4. transistor - The p - n junction

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