12FM160 Metal Diode Normal 12A 1600V

A diode designed as a semiconductor device specifically acts as a one-way switch for current. It permits the flow of current easily in one direction but severely restricts current from flowing in the opposite direction. A metal rectifier is an early version of a semiconductor with copper oxide or selenium as a semiconductor material. These diodes are widely used in power applications to convert alternating current to direct current in devices such as radios and battery chargers. Metal rectifiers are made up of washer-like discs of several metals. Which is either copper (with an oxide layer to provide the rectification) or steel or aluminium, plated with selenium. The discs are often separated by spacer sleeves to supply cooling for the device.

The principle of operation of metal rectifier is somewhat similar to the modern semiconductor rectifiers (Schottky diodes and p–n diodes).  But somewhat more complex. Both selenium and copper oxide are used as semiconductors, in practice doped by impurities during manufacture. Once they are deposited on metals, it might be expected that the result’s an easy metal-semiconductor junction which the rectification would be a result of a Schottky barrier. generated out of the cadmium-tin metal coating during processing. In any case, the result’s that there’s a depletion region within the semiconductor, with a built-in field, and this provides the rectifying action.