page_title: Diode
section_title: Semiconductor diodes
hierarchical_section_title: Diode / Semiconductor diodes
caption_attribution_description: English: The EFD108 is a point contact diode in a DO-7 type package employing N-form Germanium and gives an efficient and excellent linearity when used in FM detection, AM detection, etc.
context_page_description: A diode is a two-terminal electronic component that conducts current primarily in one direction; it has low resistance in one direction, and high resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used.
caption: Close-up of an EFD108 germanium point-contact diode in DO7 glass package, showing the sharp metal wire (cat whisker) that forms the semiconductor junction.
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