Conductor rectifier elements are made by contacting semiconductor materials with appropriate metals (or two semiconductor materials of different properties) and undergoing technical processing to form a P-N junction. If a voltage is applied to both ends of the P-N junction, when the positive end of the voltage is connected to the P-type layer and the negative end is connected to the N-type layer, the resistance of the junction is very small; when the polarity of the external voltage is opposite, the resistance of the junction is very large. Since semiconductor rectifier elements have such strong asymmetric conductivity (in fact, they can be considered to have unidirectional conductivity), they can play a rectifying role.
Semiconductor rectifier elements have a simple structure, are easy to use and maintain, have a long life, and are small in size, so they are currently widely used in rectifiers.
Semiconductor rectifier elements are divided into several types of rectifier elements, such as germanium, silicon, selenium, copper oxide, and copper sulfide, according to the semiconductor elements used. Among them, copper oxide and copper sulfide rectifier elements are only used in special occasions because of their poor rectification performance.
Germanium and silicon rectifier elements are often called germanium and silicon diodes, respectively. This type of diode is divided into point-contact type, surface junction type, and planar type according to the structural form. The latter two are mainly used as rectifying elements.