Rectifier diodes are two-terminal electronic componentsthat allow current to flow in only one direction, from an anode ( )to a cathode (-), and that convert AC to DC. These simplesemiconductors are PN junctions with a positive or P-region withpositive ions and a negative or N-region with negative electrons.Applying voltage to the PN junction causes current to flow in onlyone direction as electrons from the N-region fill “holes” in theP-region. Typically, rectifier diodes are made of semiconductormaterials such as silicon, germanium or selenium.