Most of the most common diodes today are made of semiconductor materials such as silicon or germanium.
Diode, (English: diode), among electronic components, is a device with two electrodes, which only allows current to flow in a single direction, and many uses are to apply its rectification function. The Varicap Diode is used as an electronic adjustable capacitor. The current directionality of most diodes is usually called "Rectifying" function. The most common function of diode is to allow current to pass only in a single direction (called forward bias) and block it in the reverse direction (called reverse bias). Therefore, the diode can be thought of as an electronic version of the check valve.
types of diodes there are many types of diodes, which can be divided into germanium diodes (Ge tubes) and silicon diodes (Si tubes) according to the semiconductor materials used. According to its different uses, it can be divided into early vacuum electronic diodes such as detector diode, rectifier diode, zener diode, switching diode, isolation diode, Schottky diode and light-emitting diode. It is an electronic device that can conduct current in one direction. There is a PN junction and two lead terminals in the semiconductor diode. This electronic device has unidirectional current conductivity according to the direction of applied voltage. Generally speaking, a crystal diode is a p-n junction interface formed by sintering a P-type semiconductor and an N-type semiconductor. Space charge layers are formed on both sides of the interface to form a self-built electric field. When the applied voltage is equal to zero, the diffusion current is equal to the drift current caused by the self-built electric field due to the concentration difference of carriers on both sides of the p-n junction, which is also the normal diode characteristic.
early diodes included "Cat's Whisker" Crystals" and vacuum tubes (called "thermal valves" in Britain). Nowadays, most common diodes use semiconductor materials such as silicon or germanium.