Diode

A diode can be thought of as the electronic version of a one-way valve. By restricting the direction of movement of charge carriers, it allows an electric current to flow in one direction, but essentially blocks it in the opposite direction.

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Diodes may be made from semiconductor materials such as silicon or germanium or may be fabricated using devices depending on thermionic emission: tubes (US) (or valves in UK).

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The first diodes were vacuum tube devices (also known as thermionic valves), arrangements of electrodes surrounded by a vacuum within a glass envelope, similar in appearance to incandescent light bulbs. The arrangement of a filament and plate as a diode was invented in 1904 by John Ambrose Fleming (scientific adviser to the Marconi company) based on an observation by Thomas Edison. Like light bulbs, vacuum tube diodes have a filament through which current is passed, heating the filament. When heated, the filament can emit electrons into the vacuum. These electrons are electrostatically drawn to a positively charged outer metal electrode called the anode, or "plate". Few electrons flow from the plate back toward the filament, even if the charge on the plate is made negative, because the plate is not heated and therefore does not eject many electrons by thermionic emission.

Electronic: Electronic can refer to many things:...

One-way valve: redirect check valve...

Charge carrier: Charge carrier denotes in physics a free (mobile, unbound) particle carrying an electric charge. Examples are electrons and ions. In semiconductor physics, the travelling vacancies in the valance-band electron population (holes) are treated as charge carriers....